Court Opinion

ID: 4663706
Source: CourtListenerOpinion
Date Created: 2021-03-01 13:06:17.08375+00
Date Added: 2024-06-11T08:02:30.829543
License: Public Domain

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SJC-12921

     SETH DOULL1 & another2    vs.   ANNA C. FOSTER & another.3

         Franklin.      October 5, 2020. - February 26, 2021.

   Present:    Budd, C.J., Gaziano, Lowy, Cypher, & Kafker, JJ.

Negligence, Medical malpractice, Causation, Standard of care.
     Medical Malpractice, Standard of care, Consent to medical
     treatment. Practice, Civil, Instructions to jury,
     Amendment of complaint, Interrogation of jurors.

     Civil action commenced in the Superior Court Department on
May 28, 2014.

     The case was tried before Mary-Lou Rup, J., and a motion
for a new trial was considered by her.

     The Supreme Judicial Court on its own initiative
transferred the case from the Appeals Court.

     Krzysztof G. Sobczak for the plaintiffs.
     Tory A. Weigand for the defendants.
     Jennifer A. Creedon & Stephanie M. Gazda, for Massachusetts
Defense Lawyers Association, amicus curiae, submitted a brief.

     1 Individually, as personal representative of the estate of
Laura Doull, and as next friend of Troy Doull.

     2   Megan Doull.
     3   Robert J. Miller.
                                                                      2

     Brendan G. Carney, Thomas R. Murphy, Kevin J. Powers, &
Elizabeth N. Mulvey, for Massachusetts Academy of Trial
Attorneys, amicus curiae, submitted a brief.

     KAFKER, J.    Causation has been a continually contested

concept in tort law, confounding courts, commentators, and

practitioners.    In this medical malpractice case, we are asked

once again to clarify our case law on causation, along with a

series of other issues that are more readily decided.

Specifically, we examine the use of two competing causation

standards:   the traditional but-for causation standard and the

alternative substantial contributing factor standard.    After

careful review, we conclude that the traditional but-for factual

causation standard is the appropriate standard to be employed in

most cases, including those involving multiple alleged causes.

This is the approach recommended by the Restatement (Third) of

Torts:   Liability for Physical and Emotional Harm (2010)

(Restatement [Third]).    In doing so, we conclude that the

substantial factor test is unnecessarily confusing and

discontinue its use, even in multiple sufficient cause cases.

Because the jury in this case were instructed using traditional

but-for causation principles, the instructions were proper.      We
                                                                     3

also reject all of the plaintiffs' other claims on appeal and

affirm the order denying a new trial.4

     1.   Background.    We summarize the facts that could have

been found by the jury, reserving certain facts for later

discussion.

     a.   Facts.   Between 2008 and 2011, Laura Doull was a

patient of Anna C. Foster, a nurse practitioner, and her

supervisor, Dr. Richard J. Miller (collectively, the

defendants).   Miller, an internist, owned the medical practice

where Doull was a patient.

     In August 2008, Doull had an appointment with Foster to

seek advice regarding perimenopause-related symptoms.     Foster

prescribed Doull a topically applied, naturally derived

progesterone cream to treat the symptoms.5    Foster admitted that

she did not document any conversation that she had with Doull

about the risks and benefits of, or the alternatives to, the

progesterone cream, but she did testify that they discussed

alternatives to it.     However, Foster stated that she did not

     4 We acknowledge the amicus briefs submitted by the
Massachusetts Academy of Trial Attorneys and the Massachusetts
Defense Lawyers Association.
     5 Progesterone is a hormone that humans naturally produce.
Supplementing the progesterone that the human body produces is a
form of hormone replacement therapy typically used to treat
menopause- or perimenopause-related symptoms. Progesterone
supplements come in both synthetic and naturally derived forms.
                                                                    4

discuss the possibility with Doull that the progesterone cream

could cause blood clots because she did not consider this to be

a risk.    Doull continued to use the progesterone cream through

the spring of 2011.

     Earlier that spring, Doull had visited Miller's practice on

three separate occasions to complain about shortness of breath.

Doull met with Foster on each visit, and Foster performed a

physical examination of Doull each time.    Doull had a history of

asthma and allergies.    At the spring 2011 visits, Foster

diagnosed Doull's shortness of breath as a symptom of some

combination of these long-standing conditions.    Miller did not

examine Doull during any of these visits.

     In May 2011, Doull had a "seizure-like event" and was

transported to the hospital.    At the hospital, she was diagnosed

with a pulmonary embolism, a condition where blood clots or

other substances block portions of the pulmonary arteries in the

lungs.    A pulmonary embolism may cause shortness of breath as

well as chronic thromboembolic pulmonary hypertension (CTEPH), a

rare disease where pressure in the pulmonary artery increases

and causes the heart to fail.   Indeed, that May, Doull was

diagnosed with CTEPH.    A lung scan revealed that blood clots in

Doull's lungs were chronic.

     In November 2011, Doull underwent surgery in an attempt to

remove the blockage from her lungs, but the procedure proved
                                                                   5

unsuccessful.    After the surgery, Doull was prescribed various

medications to treat the pulmonary hypertension that had

resulted from her CTEPH.   None of these medications abated the

disease.    In 2015, Doull died from complications arising from

CTEPH.    She was forty-three years old.

     b.    Procedural history.   Prior to her death, Doull and

various family members (collectively, the plaintiffs) commenced

this suit against the defendants, claiming negligence, failure

to obtain informed consent, and loss of consortium.6    Four months

before trial, the plaintiffs moved to amend their complaint to

include the manufacturer of the progesterone cream, Women's

International Compounding Inc. (WIC), as a defendant.    The trial

judge denied the plaintiffs' motion.

     At trial, the plaintiffs argued that Miller and Foster

failed to obtain informed consent from Doull concerning the

progesterone cream's risks and alternatives, that Foster failed

to diagnose Doull's pulmonary embolism during the spring 2011

visits, and that Miller failed to supervise Foster adequately

during all relevant times.

     To support these claims, Dr. Paul Genecin, a primary care

internal medicine physician and the plaintiffs' expert witness,

testified that natural progesterone was not any safer than

     6 Doull's estate continued to prosecute the claims after her
death, amending the complaint to add a wrongful death claim.
                                                                   6

synthetic derivations of the hormone, and that the cream likely

caused Doull to develop blood clots.   Genecin also testified

that Foster had failed to investigate adequately Doull's

shortness of breath complaints during the spring 2011 visits.

He testified that diagnosis of Doull's pulmonary embolism during

the spring of 2011 could have prevented the onset of CTEPH, and

that Miller's failure to supervise Foster's actions constituted

a breach of the duty of care.

     Dr. Nicholas S. Hill, a pulmonologist and an expert for the

defense, testified that there was "no evidence anywhere that

indicates that progesterone cream applied to the skin increases

the risk of clotting."   Hill also disagreed with Genecin's

assessment that Doull's CTEPH would have been preventable had

Foster diagnosed it during the spring 2011 visits.

Specifically, Hill testified that by the time Doull was

diagnosed with CTEPH in May 2011, the disease "had been going on

for a long time, probably months at least."   According to Hill,

the chronic nature of Doull's blood clots meant that her outcome

would have remained the same had Foster diagnosed her with the

disease during the spring of 2011.

     The jury returned a verdict for the defendants and answered

various special questions.   First, the jury found that the

defendants had not failed to acquire informed consent from Doull

with respect to the progesterone cream.   Second, although the
                                                                     7

jury did find that Foster negligently failed to diagnose Doull's

pulmonary embolism, they found that this negligence was not the

cause of either the harms suffered by Doull after her seizure -

like event in 2011 or her death in 2015.    Finally, the jury

found that Miller had been negligent in his supervision of

Foster, but that this negligence, too, had not harmed Doull.

     Before the jury returned its verdict, the defendants filed

a motion to require judicial approval for postverdict contact

with jurors, which the judge granted.     After the verdict, the

plaintiffs filed a motion for a new trial, which the judge

denied.   The plaintiffs then appealed.    We transferred the case

from the Appeals Court to this court on our own motion.

     2.   Discussion.    "We review the denial of a motion for a

new trial for an abuse of discretion, bearing in mind that a

judge should exercise his or her discretion only when the

verdict is so greatly against the weight of the evidence as to

induce in his [or her] mind the strong belief that it was not

due to a careful consideration of the evidence, but that it was

the product of bias, misapprehension or prejudice" (quotation

and citation omitted).    DaPrato v. Massachusetts Water Resources

Auth., 482 Mass. 375, 377 n.2 (2019).

     a.   Jury instructions.   "In a civil trial, a judge should

instruct the jury fairly, clearly, adequately, and correctly

concerning principles that ought to guide and control their
                                                                        8

action" (quotation and citation omitted).           DaPrato, 482 Mass. at

383 n.11.    "The judge is not bound to instruct in the exact

language of the [parties'] requests, however, and has wide

latitude in framing the language to be used in jury instructions

as long as the instructions adequately explain the applicable

law" (quotation and citation omitted). Id.    When reviewing jury

instructions, an "appellate court considers the adequacy of the

instructions as a whole, not by fragments" (citation omitted).
Id.

      The plaintiffs argue that they are entitled to a new trial

based on several allegedly erroneous jury instructions regarding

the defendants' negligence.     We consider these claims in turn.

      i.    Jury instructions on causation.    The plaintiffs claim

that the judge's instruction on the element of causation was

erroneous.     The judge instructed the jury using a but-for

standard for factual causation.    Specifically, the judge

instructed:

      "With regard to this issue of causation, the Defendant in
      question's conduct was a cause of the Plaintiff's harm,
      that is Laura Doull's harm, if the harm would not have
      occurred absent, that is but for the Defendant's
      negligence. In other words, if the harm would have
      happened anyway, that Defendant is not liable."

The plaintiffs argue that the judge was required to instruct the

jury on a substantial contributing factor standard, instead of

this but-for standard, because there were several possible
                                                                      9

causes of -- and multiple tortfeasors involved in -- Doull's

injuries and death.    The defendants disagree, contending that

the instruction given was consistent with both Massachusetts law

and the approach taken by the Restatement (Third). 7   Because the

plaintiffs objected to the instruction given by the trial judge,

we review for prejudicial error.     DaPrato, 482 Mass. at 384.

     We conclude that the but-for standard was the appropriate

standard in this case and therefore there was no error.     We also

clarify infra how a jury should be instructed on causation in

negligence cases involving multiple potential causes of harm.

     A.   But-for causation.    We begin with basic causation

principles.   It is a bedrock principle of negligence law that a

defendant cannot and should not be held liable for a harm unless

the defendant caused the harm.     See Wainwright v. Jackson, 291
Mass. 100, 102 (1935) ("The general rule is that one cannot be

held liable for negligent conduct unless it is causally related

to injury of the plaintiff").    See also Glidden v. Maglio, 430
Mass. 694, 696 (2000) (causation "is an essential element" of

proof of negligence).    Causation has traditionally involved two

separate components:    the defendant had to be both a factual

cause (or "cause in fact") and a legal cause of the harm.       See

Leavitt v. Brockton Hosp., Inc., 454 Mass. 37, 45 (2009)

     7 We also solicited amicus briefs on whether to adopt the
factual causation standard from the Restatement (Third).
                                                                    10

("Liability for conduct obtains only where the conduct is . . .

a cause in fact of the injury and where the resulting injury is

within the scope of the foreseeable risk arising from the

negligent conduct"); Kent v. Commonwealth, 437 Mass. 312, 320

(2002), citing Wallace v. Ludwig, 292 Mass. 251, 254 (1935)

(negligent conduct must be both "cause in fact of the injury" as

well as "legal cause of the injury").     Legal causation is also

commonly referred to as "proximate causation."     The Restatement

(Third) describes this aspect of the causation inquiry as

whether the defendant's conduct was within the "scope of

liability."   See Restatement (Third) § 26 comment a (explaining

terminology changes from prior Restatements).

     Generally, a defendant is a factual cause of a harm if the

harm would not have occurred "but for" the defendant's negligent

conduct.   See W.L. Prosser & W.P. Keeton, Torts § 41, at 265

(5th ed. 1984) ("An act or an omission is not regarded as a

cause of an event if the particular event would have occurred

without it").   See, e.g., Hollidge v. Duncan, 199 Mass. 121, 124

(1908) (affirming determination that plaintiff's injuries would

not have occurred "but for the defendant's negligence").    See

also Reporters' Note to Restatement (Third) § 26 comment b

(collecting authorities demonstrating that "but-for test is

central to determining factual cause").    This long -standing

principle ensures that defendants will only be lia ble for harms
                                                                  11

that are actually caused by their negligence and not somehow

indirectly related to it.   See Callahan v. Cardinal Glennon

Hosp., 863 S.W.2d 852, 862 (Mo. 1993) ("Any attempt to find

liability absent actual causation is an attempt to connect th e

defendant with an injury or event that the defendant had nothing

to do with.   Mere logic and common sense dictate[] that there be

some causal relationship between the defendant's conduct and the

injury or event for which damages are sought").   See also

Paroline v. United States, 572 U.S. 434, 452 (2014) ("If the

conduct of a wrongdoer is neither necessary nor sufficient to

produce an outcome, that conduct cannot in a strict sense be

said to have caused the outcome"); Price Waterhouse v. Hopkins,

490 U.S. 228, 282 (1989) (Kennedy, J., dissenting) ("Any

standard less than but-for . . . represents a decision to impose

liability without causation").   Another way to think about the

but-for standard is as one of necessity; the question is whether

the defendant's conduct was necessary to bringing about the

harm.   Restatement (Third) § 26 comment b ("a factual cause can

also be described as a necessary condition for the outcome").

The majority of courts around the country and all three

Restatements have required but-for causation in most cases.     See

Reporter's Note to Restatement (Third) § 26 comment a.     See also

Restatement (Third) § 26; Restatement (Second) of Torts § 432(1)
                                                                     12

(1965) (Restatement [Second]); Restatement of Torts § 432(1)

(1939).

      Additionally, for the defendant to be liable, the defendant

must also have been a legal cause of the harm.     This means that

the harm must have been "within the scope of the foreseeable

risk arising from the negligent conduct."     Leavitt, 454 Mass. at

45.   This aspect of causation is "based on considerations of

policy and pragmatic judgment."    Kent, 437 Mass. at 320–321,

quoting Poskus v. Lombardo's of Randolph, Inc., 423 Mass. 637,

640 (1996).   These considerations are separate and distinct from

factual causation.    Kent, supra at 320.   And, together, these

concepts identify which defendants can be held liable for

negligent conduct.    This case focuses primarily on factual

causation.

      B.   Exceptions to but-for causation.   There are several

situations in which a but-for standard does not work and has

been altered to avoid unjust and illogical results.    See

Paroline, 572 U.S. at 452 ("tort law teaches that alternative

and less demanding causal standards are necessary in certain

circumstances to vindicate the law's purposes").     One is the

situation involving multiple sufficient (or overdetermined)

causes.    See Restatement (Third) § 27 comment b ("Courts and

scholars have long recognized the problem of overdetermined harm

-- harm produced by multiple sufficient causes -- and the
                                                                   13

inadequacy of the but-for standard for this situation").     The

classic example involves two separate fires merging and

destroying a house.   See generally Anderson v. Minneapolis, St.

Paul & Sault Ste. Marie Ry. Co., 146 Minn. 430 (1920).     If

either fire could have independently destroyed the home, then

neither fire could be a but-for cause of the harm (because the

home would have been destroyed by the other regardless), thereby

relieving each of liability under a but-for standard.     To avoid

this unjust result, there must be a different causation standard

in these cases.   See Restatement (Third) § 27 comment c ("A

defendant whose tortious act was fully capable of causing the

plaintiff's harm should not escape liability merely becaus e of

the fortuity of another sufficient cause").   These cases,

however, are exceedingly rare. Id. at § 27 comment b.

     The first two Restatements devised an alternative causation

standard, with its own terminology, to address this specific

problem.   In circumstances in which but-for did not work, they

treated defendants as a cause where their conduct was not a

necessary but-for cause but was rather a so-called "substantial

factor" in bringing about the harm.   Specifically, they provided

that "[i]f two forces are actively operating, one because of the

actor's negligence, the other not because of any misconduct on

his part, and each of itself is sufficient to bring about harm

to another, the actor's negligence may be found to be a
                                                                    14

substantial factor in bringing it about."    Restatement (Second)

§ 432(2).   The substantial factor terminology has, as explained

infra, proved confusing, as it seems odd to describe something

that may not have been a cause at all as a substantial factor.

Nonetheless, the terminology was devised to address the specific

problem of multiple sufficient causes where but-for causation

could not be proved.   It was not intended to displace but-for

causation more generally.    In circumstances other than multiple

sufficient causes, but-for causation was required for a

defendant to be held liable. Id. at § 432(1).

     A number of courts, including this one, have also

recognized the difficulty of proving but-for causation in toxic

tort and asbestos cases.    See O'Connor v. Raymark Indus., Inc.,

401 Mass. 586, 588-591 (1986); Morin v. AutoZone Northeast,

Inc., 79 Mass. App. Ct. 39, 42 (2011).   See also, e.g.,

Rutherford v. Owens-Ill., Inc., 16 Cal. 4th 953, 958 (1997);

Bostic v. Georgia-Pac. Corp., 439 S.W.3d 332, 353 (Tex. 2014).

In these cases, it can be difficult, if not impossible, for the

plaintiff to identify which particular exposures were necessary

to bring about the harm.    See Matsuyama v. Birnbaum, 452 Mass.
1, 30 (2008);8 O'Connor, supra, at 588-589; Welch v. Keene Corp.,

     8 Contrary to the concurrence's suggestion, we certainly are
not suggesting here that Matsuyama is an asbestos or toxic tort
case, as the sentence preceding the citation makes clear. For
                                                                     15

31 Mass. App. Ct. 157, 162 (1991).    It may be clear that a toxic

substance or asbestos caused the harm, and that the defendants

exposed the plaintiffs to the toxic substance or the asbestos,

but it may not be possible to determine which exposures were

necessary to cause the harm.     In this situation, as in multiple

sufficient cause cases, the but-for standard is inadequate, as

it could allow all defendants to avoid liability despite their

negligent exposure of the plaintiffs to the substances, as it

may not be possible to prove which exposures were necessary to

bring about the harm and which were not.     The substantial factor

test again fixes this problem by relaxing the causal requirement

and permitting liability in these circumstances.

     Instead of limiting the substantial factor test to these

two contexts where but-for causation cannot be established,

however, the first two Restatements combined the substantial

factor terminology and the but-for causation requirement in a

confusing manner.   The term "substantial factor" was employed

generally in negligence cases.    In other words, a defendant

the sake of clarity, here is the language to which we are
referring in Matsuyama -- "The 'substantial contributing factor'
test is useful in cases in which damage has multiple causes,
including but not limited to cases with multiple tortfeasors in
which it may be impossible to say for certain that any
individual defendant's conduct was a but-for cause of the harm
. . . ." (emphasis added). Matsuyama, 452 Mass. at 30. This is
the point we are making here as well, which is why we included a
citation to Matsuyama.
                                                                     16

could not be liable for negligence under the first two

Restatements unless the defendant was a "substantial factor" in

bringing about the harm.     See Restatement (Second) § 431;

Restatement of Torts § 431.    But to be a substantial factor, the

defendant also had to be a but-for cause of the harm in most

cases.    See Restatement (Second) § 432(1); Restatement of Torts

§ 432(1).    The sole exception to the but-for causation

requirement was for multiple sufficient cause cases.       The result

was to merge and confuse the but-for standard and the

substantial factor test.    It also blurred the line between

factual and legal causation.        See Restatement (Third) § 29

comment a ("The 'substantial factor' requirement . . . in the

Second Restatement of Torts has often been understood to address

proximate cause, although that was not intended").

     C.     Multiple cause cases.    Against this background, the

plaintiffs urge, and some of our prior cases suggest, that a

substantial contributing factor standard should be used whenever

there are multiple potential causes of a harm.        We conclude,

however, that a but-for standard is the proper standard in most

negligence cases, as but-for causes can be identified and

conduct that had no causal effect can be excluded.

     There is a significant difference between multiple

sufficient cause and toxic tort cases and other cases involving

multiple potential causes.     In multiple sufficient cause cases,
                                                                     17

the existence of two independently sufficient causes means that

we cannot identify a but-for cause even though there are

multiple tortfeasors who would have caused the harm on their

own.    In the absence of one of the causes, the other cause would

still have been sufficient to bring about the harm.     Similarly,

in toxic tort cases, although but-for causation may be

theoretically sound, it is nearly impossible for a plaintiff or

a jury to determine with any certainty which exposures were

necessary to bring about the harm and which were not.    Using a

strict but-for standard in these cases may frustrate the ability

of plaintiffs to recover for negligent conduct that caused their

harm, because of the happenstance of multiple defendants

engaging in negligent acts each of which alone may be sufficient

to cause the harm, and the impossibility of proving which of the

negligent acts were but-for causes.    Thus, if anyone is to be

held liable for these harms, there must be an exception to the

but-for standard.    The concern uniting these two types of cases

is the great difficulty, if not impossibility, of identifying

but-for causes of the harm.

       This concern is not present in most cases involving

multiple alleged causes, however.    There is nothing preventing a

jury from assessing the evidence and determining which of the

causes alleged by the plaintiff were actually necessary to bring

about the harm, and which had nothing to do with the harm.
                                                                    18

Indeed, this case shows that the but-for test works well even

when a plaintiff alleges that there are multiple causes of a

harm.     Here, the plaintiffs alleged that the various negligent

acts of the defendants caused Doull's harm and eventual death.

The jury were instructed on a but-for standard.9    As explained

above, the purpose of this but-for standard is to separate the

conduct that had no impact on the harm from the conduct that

caused the harm.     The jury ultimately did just that -- it

concluded that the defendants did not cause the harm even though

they committed a breach of their duties by failing to diagnose

her pulmonary embolism.    Tort law has long made this causal

connection a prerequisite for imposing liability.     Here, using a

but-for standard, the jury concluded that no such connection

existed between the defendant's conduct and Doull's harm and

death.10    This shows how, even in a case involving multiple

     9 The judge instructed the jury that "[the] conduct was a
cause of the Plaintiff's harm, that is Laura Doull's harm, if
the harm would not have occurred absent, that is but for the
Defendant's negligence. In other words, if the harm would have
happened anyway, that Defendant is not liable."
     10Indeed, as described above, the defendants' expert
testified that Doull's outcome would not have been different
even if Foster had diagnosed her condition in May 2011. The
jury appear to have credited this testimony, as it would explain
why the jury concluded that Foster, despite her negligence, did
not cause Doull's harm. In this way, expert testimony will
often be significant in cases involving multiple potential
causes, as it will help the jury distinguish between causes that
were necessary to bring about the harm and causes that were not.
                                                                   19

causes in which the plaintiffs argue it was error not to use the

substantial contributing factor test, the but-for standard did

what it is supposed to do and prevented the defendants from

being held liable where the jury concluded that they did not

cause the harm.   Indeed, these types of cases, alleging multiple

causes, may be where the but-for test is most important and

useful, as it serves to separate the necessary causes from

conduct that may have been negligent but may have had nothing to

do with the harm caused.

     One source of confusion is the mistaken belief that there

can only be a single but-for cause of a harm.11   Indeed, the

plaintiffs argue that the presence of multiple potential causes

here means that no one cause could be the "sole/but -for" cause.

But there is no requirement that a defendant must be the sole

factual cause of a harm.   See Reporters' Note to Restatement

(Third) § 26 comment c ("That a party's tortious conduct need

only be a cause of the plaintiff's harm and not the sole cause

is well recognized and accepted in every jurisdiction").     See

also, e.g., Bostock v. Clayton County, 140 S. Ct. 1731, 1739

(2020) ("[But-for causation] can be a sweeping standard.     Often,

     11For an example of this confusion, look no further than
the concurrence. The concurrence thinks that by instructing the
jury that there could be more than one but-for cause, we are
creating a whole new standard separate and apart from the but -
for standard -- a "but-for plus" standard. See post at     .
                                                                    20

events have multiple but-for causes"); June v. Union Carbide

Corp., 577 F.3d 1234, 1242 (10th Cir. 2009) ("A number of

factors [often innocent] generally must coexist for a

tortfeasor's conduct to result in injury to the plaintiff. . . .

That there are many factors does not mean that the defendant 's

conduct was not a cause").

       In fact, there is no limit on how many factual causes there

can be of a harm.    Restatement (Third) § 26 comment c ("there

will always be multiple . . . factual causes of a harm, although

most will not be of significance for tort law and many will be

unidentified").     The focus instead remains only on whether, in

the absence of a defendant's conduct, the harm would have still

occurred.    See id. ("The existence of other causes of the harm

does not affect whether specified tortious conduct was a

necessary condition for the harm to occur").     This is not a high

bar.    See id. at § 26 comment i ("Quite often, each of the

alleged acts or omissions is a cause of the harm, i.e., in the

absence of any one, the harm would not have occurred").     And

acknowledging the potential for multiple but-for causes

"obviates any need for substantial factor as a test for
                                                                  21

causation."   Reporters' Note to Restatement (Third) § 26

comment j.12,13

     The terminology of the substantial factor standard also

leads to confusion.   See Restatement (Third) § 26 comment j

("The substantial-factor test has not, however, withstood the

test of time, as it has proved confusing and been misused").

See also Sanders, Green, & Powers, The Insubstantiality of the

"Substantial Factor" Test for Causation, 73 Mo. L. Rev. 399, 430

(2008) (substantial factor test "gives no clear guidance to the

factfinder about how one should approach the causal problem" and

"permits courts to engage in fuzzy-headed thinking about what

     12 Where multiple causes are alleged, it is appropriate to
instruct a jury that there can be more than one factual cause of
a harm.

     13The Restatement (Third) introduces a novel concept
referred to as "causal sets," see Restatement (Third) § 26
comment c. This concept is suggested as a helpful way to think
of factual causation in a multiple cause case. It is not a
separate test and is meant to be used only if it is deemed to be
helpful. It is not an independent legal requirement. A causal
set is defined as the group of actions or conditions that were
necessary to bring about the harm. Id. ("[C]onceive of a set
made up of each of the necessary conditions for the plaintiff's
harm. Absent any one of the elements of the set, the
plaintiff's harm would not have occurred"). So, in cases where
the factual cause of a harm is an aggregate of multiple acts,
omissions, or conditions, the Restatement simply labels the
aggregate as a "causal set." It also explains that there may be
competing causal sets. See id. at § 27 comment f. Importantly,
it does not change the standard of causation -- a defendant
would still only be a factual cause if the harm would not have
occurred but for the defendant's actions.
                                                                  22

sort of causal requirement should be imposed on plaintiffs"

[emphasis omitted]).   Unsurprisingly, it has "few supporters."

Reporters' Note to Restatement (Third) § 26 comment j.14

     The drafters of the most recent Restatement concluded that

the confusing terminology has rendered the substantial factor

test potentially both too strict and too lenient as a standard

     14Indeed, as the Restatement points out, many scholars have
criticized the substantial factor test. See, e.g., Dorsaneo,
Judges, Juries, and Reviewing Courts, 53 S.M.U. L. Rev. 1497,
1528-1530 (2000) (substantial factor "render[s] the causation
standard considerably less intelligible"); Fischer, Insufficient
Causes, 94 Ky. L.J. 277, 277 (2005) ("Over the years, courts
also used the substantial factor test to do an increasing
variety of things it was never intended to do and for which it
is not appropriate. . . . [T]he test now creates unnecessary
confusion in the law and has outlived its usefulness");
Robertson, The Common Sense of Cause in Fact, 75 Tex. L. Rev.
1765, 1776 (1997) ("By using the term ["substantial factor"] in
three different senses, the Restatement [Second] of Torts has
contributed to a nationwide confusion on the matter");
Stapleton, Legal Cause: Cause-in-Fact and the Scope of
Liability for Consequences, 54 Vand. L. Rev. 941, 945, 978
(2001) ("The obfuscating terminology of legal cause, proximate
cause, and substantial factor should be replaced . . .");
Wright, Once More into the Bramble Bush: Duty, Causal
Contribution, and the Extent of Legal Responsibility, 54 Vand.
L. Rev. 1071, 1080 (2001). See also H.L.A. Hart & T. Honoré,
Causation in the Law 124 (2d ed. 1985) ("Little, however, seems
to be gained by describing, even to a jury, such cases in terms
of the admittedly indefinable idea of a 'substantial factor'");
W.L. Prosser & W.P. Keeton, Torts § 41, at 43-45 (5th ed. Supp.
1988) ("Even if substantial factor' seemed sufficiently
intelligible as a guide in time past, however, the development
of several quite distinct and conflicting meanings for the term
'substantial factor' has created a risk of confusion and
misunderstanding, especially when a court, or an advocate or
scholar, uses the phrase without indication of which of its
conflicting meanings is intended").
                                                                  23

of factual causation.   See Restatement (Third) § 26 comment j.

The use of the word "substantial" imposes a more demanding

standard than a traditional but-for standard.     The current model

jury instruction in Massachusetts explains that "substantial"

means that the defendant's negligence was "not an insignificant

factor" and that "it must be a material and important ingredient

in causing the harm."   Massachusetts Superior Court Civil

Practice Jury Instructions § 4.3.4(b) (Mass. Cont. Legal Educ.

3d ed. 2014).   There may be policy reasons to impose a more

rigorous standard for factual cause than but-for causation, but

that was not the primary purpose of the substantial factor test.

See Restatement (Third) § 26 comment j.15   Limits on liability

have also been considered to be properly addressed through the

lens of legal causation, not factual causation.    If a

defendant's conduct was necessary to bring about a harm, and the

harm would not have occurred without the defendant's conduct,

     15 The concurrence argues that the substantial contributing
factor standard enhances the fairness of a negligence trial.
Post at     . We are not sure why this is true, particularly
from the injured party's perspective, if both factual and legal
causation are otherwise satisfied. The injured party has
suffered a harm, and but for the defendant's conduct the harm
would not have occurred. Regardless, we historically address
the equities of recovery in the legal causation, not the factual
causation, inquiry. See Kent, 437 Mass. at 320–321.
                                                                  24

that defendant should be treated as a factual cause of the

harm.16

     Conversely, the confusing terminology has been found to

invite jurors to skip the factual causation inquiry altogether.

Although terms like "substantial factor" or "substantial

contributing factor" would seem to imply some level of causal

connection, their employment without a but-for causation

instruction in cases in which but-for causation can be

established invites the jury to skip this step in the analysis

and impose liability on someone whose negligence lacks the

requisite causal effect.17   See Reporters' Note to Restatement

(Third) § 26 comment j (substantial factor test "may unfairly

permit proof of causation on less than a showing that the

tortious conduct was a but-for cause of harm").   Absent a but-

for requirement, a jury presented with negligence that is

"substantial" may decide to impose liability without coming to

     16If the cause is truly trivial, it can be excluded from
legal causation on that ground. See Reporters' Note to
Restatement (Third) § 26 comment j. See also Restatement
(Third) § 36. Again, the Restatement (Third) approach is more
straightforward, as it allows a jury to excuse a defendant from
liability on legal causation grounds where the defendant's
conduct is determined to be trivial. See Restatement (Third)
§ 36.
     17In fact, we indicated in O'Connor, 401 Mass. at 591, that
in a case where a substantial contributing factor instruction is
given, it would be error for the judge to instruct the jury in a
way that requires it to find that the defendant was a but-for
cause of the harm.
                                                                    25

terms with whether the negligence was even a cause of the harm.

As determining causation may be even more difficult where

multiple causes are alleged, we need to be sure juries do not

skip this step.

     The use of substantial factor language also conflates and

collapses the concepts of factual and legal causation.     See,

e.g., Strassfeld, If . . . :     Counterfactuals in the Law, 60

Geo. Wash. L. Rev. 339, 355 (1992) (substantial factor approach

"smuggles noncausal policy considerations, which normally are

confined to the duty or proximate cause analysis, into the

analysis of factual causation," and thus it "is either

contentless, or it reintroduces and complicates [factual

causation]").     See also Reporters' Note to Restatement (Third)

§ 26 comment a ("The conflation of factual cause and proximate

cause by the Torts Restatements has been criticized since

shortly after the first Restatement of Torts was published") .

Instructing the jury to only consider "substantial factors" as

causes inserts a high degree of subjectivity as to what is

substantial and what is not, precisely the types of policy

considerations that animate our legal causation jurisprudence.

Such considerations, therefore, should not be incorporated into

the factual causation analysis as well.

     If the substantial factor test is employed whenever

multiple causes are alleged, as the plaintiffs argue, the
                                                                       26

potential for confusion is significant.     Plaintiffs often allege

multiple causes of a harm.     Restatement (Third) § 26 comment i

("Frequently, plaintiffs allege that multiple tortious acts or

omissions caused their harm.     This is especially true in

negligence actions because of the flexibility of the reasonable -

care standard").     Moreover, defendants may inject further

complexity by alleging that the plaintiffs, another defendant,

or a nonparty caused the harm.     If a substantial factor

instruction is required whenever there is more than one

potential cause, then the substantial factor standard could

supplant the but-for standard as the primary standard for

factual causation.    What originated as an exception to but-for

causation would swallow the rule.

     Finally, using a different causation standard in multiple

cause cases puts trial judges in difficult positions.        Despite

the apparent overlap, these are different standards.     There is

no simple, workable definition of "multiple causes" given that

many cases will involve multiple potential causes.     Using the

substantial contributing factor test in this manner would mean

that judges would have to decide which instruction is
                                                                   27

appropriate before instructing the jury, a task rife with

difficulty and potential error.18

     In sum, although the substantial factor test has proved

useful in two specific situations, it has not been widely

adopted as the causation standard in all negligence cases and

has been abandoned by the Restatement itself.    See Restatement

(Third) § 26 comment a.19

     In light of the foregoing, we conclude that a but-for

standard, rather than a substantial factor standard, is the

appropriate standard for factual causation in negligence cases

involving multiple alleged causes of the harm.    We see no reason

     18The concurrence disagrees with our assessment, saying
instead that we are "abandon[ing] . . . our steady and
successful practice of applying substantial contributing factor
in torts cases involving all sorts of fact patterns." Post at
. Beyond the concurrence's own appraisal of the situation, it
is not clear what evidence, empirical or otherwise, there is
that the use of the standard has been "steady and successful."
Our review of the record here supports our concern that having
two standards places trial judges in a difficult position
regarding jury instructions. Indeed, when forced to decide
which standard to use, the experienced and capable trial judge
in this case observed, "Well . . . I know that the law has been
somewhat confused in some people's eyes . . . following the
Matsuyama decision."
     19It appears that the majority of jurisdictions -- over
two-thirds -- require proof of but-for causation in the majority
of cases. At least one jurisdiction has replaced the
"substantial factor" standard with the Restatement (Third)
approach. See Thompson v. Kaczinski, 774 N.W.2d 829, 839 (Iowa
2009).
                                                                  28

to depart from but-for causation in these cases.20   Thus, in the

majority of negligence cases, the jury should be instructed on

factual cause using a but-for standard as well as legal

causation.   In this case, the judge did exactly that, making the

instructions proper.

     D.   Eliminating the substantial contributing factor test.

In addition to not extending the substantial factor test to all

cases involving multiple causes, there is good reason to replace

it with the standard proposed in the Restatement (Third) for

     20The concurrence minimizes the numerous extensive
critiques of the substantial factor test. To counteract all of
this criticism, it relies on a passing positive reference to the
standard as "useful" in dictum in Matsuyama, 452 Mass. at 30,
which was focused on the utility of the standard when but-for
causation cannot be established. As we have explained today,
however, but-for causation works perfectly well in most cases,
including those involving multiple causes.

     The concurrence also suggests that we are somehow simply
following academic fashion in adopting the Restatement (Third).
See post at    . This statement ignores that the substantial
factor test originated with the Restatement and that the case
law the concurrence cites, including Matsuyama, has demonstrated
great respect for the development of the law as reflected by the
Restatements of Torts. See, e.g., O'Connor, 401 Mass. at 591-
592 (citing Restatement [Second] §§ 430, 431, and 433); Bernier
v. Boston Edison Co., 380 Mass. 372, 386 (1980) (citing
Restatement [Second] § 435); Quinby v. Boston & Me. R.R., 318
Mass. 438, 444 (1945) (citing Restatement of Torts §§ 431 and
433); Vigneault v. Dr. Hewson Dental Co., 300 Mass. 223, 229
(1937) (citing Restatement of Torts § 432). We turn to the
Restatement not because it is fashionable to do so, but because
the American Law Institute has struggled greatly with the
complicated question of causation in negligence cases and is
constantly trying to improve the legal standard in this area,
including recognizing its own errors in this regard.
                                                                29

multiple sufficient cause cases.21   If there must be an exception

to but-for causation in cases where the but-for standard fails,

we should simply recognize such an exception rather than

adopting an entirely different causation standard with confusing

terminology and unexpected difficulties.   The approach proposed

by the Restatement (Third) does exactly that.   See State v.

Tibble, 790 N.W.2d 121, 127 n.2 (Iowa 2010) (Restatement [Third]

     21The issue of causation in toxic tort and asbestos cases
is not before us in this case. Therefore, we do not disturb our
decision in O'Connor or the use of the substantial contributing
factor instruction in those cases. In an appropriate case,
however, we may consider whether to replace the substantial
contributing factor test in these cases as well. There appears
to be a variety of approaches taken in these cases, and a
decision on whether to replace the substantial contributing
factor test would benefit from full briefing and argument.

     The concurrence misunderstands the court's hesitance to
abandon the substantial contributing factor test in asbestos and
other toxic tort cases. As we have explained, because of the
unique features of these cases, there may be factual and
scientific limitations on a plaintiff's ability to establish the
requisite causal connection between the harm and an individual
defendant. Thus, a but-for standard has seemed ill-suited for
such cases.

     It is simply not clear whether the concerns we have with
the substantial contributing factor test justify eliminating it
in these cases. Given the volume of these cases, their great
importance, and the idiosyncrasies that make them unique with
regard to factual causation, it would be unwise to apply our
holding to these cases as well without first having the benefit
of full briefing and argument. Our hesitance, however, should
not be taken as a continuing endorsement of the substantial
factor approach in toxic tort cases given the concerns we have
expressed today.
                                                                  30

§ 27 is "straightforward rule" in multiple sufficient cause

cases).

     Therefore, in the rare cases presenting the problem of

multiple sufficient causes, the jury should receive additional

instructions on factual causation.    Such instructions should

begin with the illustration from the Restatement (Third) of the

twin fires example so that the complicated concept ca n be more

easily understood by the jury.22    After the illustration, the

jury should be instructed, "A defendant whose tortious act was

fully capable of causing the plaintiff's harm should not escape

liability merely because of the happenstance of another

sufficient cause, like the second fire, operating at the same

time."    The jury should then be instructed that when "there are

two or more competing causes, like the twin fires, each of which

is sufficient without the other to cause the harm and each of

     22   That illustration is as follows:

     "Rosaria and Vincenzo were independently camping in a
     heavily forested campground. Each one had a campfire, and
     each negligently failed to ensure that the fire was
     extinguished upon retiring for the night. Due to unusually
     dry forest conditions and a stiff wind, both campfires
     escaped their sites and began a forest fire. The two
     fires, burning out of control, joined together and engulfed
     Centurion Company's hunting lodge, destroying it. Either
     fire alone would have destroyed the lodge. Each of
     Rosaria's and Vincenzo's negligence is a factual cause of
     the destruction of Centurion's hunting lodge."

Restatement (Third) § 27 comment a, illustration 1.
                                                                     31

which is in operation at the time the plaintiff's harm occurs,

the factual causation requirement is satisfied."   See

Restatement (Third) § 27 comment a.   In such cases, where there

are multiple, simultaneously operating, sufficient causes, the

jury do not have to make a but-for causation finding.    This

approach avoids the confusing terminology presented by the terms

"substantial factor" or "substantial contributing factor."      It

also eliminates the risk of the judge instructing the jury on

the wrong standard, as this instruction supplements the but-for

standard without conflicting with it.23

     We recognize that the substantial factor test is a familiar

standard in Massachusetts and that it has been used in the past,

arguably with our endorsement, albeit for specific purposes.

     23The concurrence reads our opinion as providing "not one
standard of factual causation but many," including "basic but
for," "but for plus", and "the new instruction on [multiple
sufficient cause] cases." Post at     . This is incorrect. See
parts 2.a.i.C and 2.a.i.D, supra ("in the majority of negligence
cases, the jury should be instructed on factual cause using a
but-for standard"; "in the rare cases presenting the problem of
multiple sufficient causes, the jury should receive additional
instructions on factual causation" [emphases added]). There is
no "but-for plus"; we merely make clear what nearly every other
jurisdiction recognizes -- that there is no requirement that a
defendant be the sole factual cause of the harm. See Reporter's
Note to Restatement (Third) § 26 comment c. With the exception
of toxic tort cases, see note 21, supra, and the exceedingly
rare multiple sufficient cause cases, the but-for standard will
be the standard for factual causation. The other instructions
we provide today merely clarify or expand on that concept in
appropriate cases.
                                                                   32

See, e.g., Matsuyama, 452 Mass. at 30-31.   That we have used

this standard before, however, does not automatically mean that

we should continue to do so.   In fact, given that the

Restatements are the source of this standard, 24 the Restatement

(Third)'s own recent criticism and rejection of this standard

based on its confusing application provide good reason to

reconsider its use.   Having thoroughly considered these

standards now, we conclude that the substantial contributing

factor test should no longer be used in most negligence cases.

     ii.   Jury instructions on standard of care and breach.

Next, the plaintiffs claim that the jury instructions improperly

emphasized reliance on expert testimony for establishing the

standard of care and breach regarding informed consent, citing

to the following portions of the jury instructions as

problematic:

     "In determining the -- the standard of care that applied at
     the time Nurse Practitioner Foster and Dr. Miller treated
     Laura Doull you must -- you must consider the testimony of
     the witnesses who offered their expert opinions on the
     applicable standard of care. That is, Dr. Genecin, Dr.
     Hill, Dr. Kenneth Miller and Dr. Potter. You do not decide
     on your own what the standard of care is or should have
     been, what it ought to have been. You must decide the
     standard of care based on the testimony of those witnesses.
     And obviously, as I said earlier, if there's conflict
     between the -- their opinions as to what the standard of

     24Early Massachusetts cases using a substantial factor
standard relied on the first Restatement. See, e.g., Quinby,
318 Mass. at 444; Vigneault, 300 Mass. at 229; McKenna v.
Andreassi, 292 Mass. 213, 218 (1935). We also relied on the
Restatement (Second) in O'Connor, 401 Mass. at 592.
                                                                 33

     care is, your role is to determine which opinion you credit
     in that regard.

     "You may also consider, and should also consider, any
     medical resources that may have been available to Dr.
     Miller and to Nurse Practitioner Foster during the time
     period that they were treating Laura Doull as one aspect of
     the skill and care required of them at the time. . . . You
     make that determination [of the standard of care] from all
     of the evidence introduced during the trial as well as, as
     I said, you must take into account the -- the testimony of
     the four medical experts and their testimony with regard to
     what the standard of care was."

     The plaintiffs contend that the trial judge was required to

instruct the jury that the standard of care could come from

regulations, specifically 244 Code Mass. Regs. § 9.04(5)

(2000),25 and that breach could be established through an

admission of fault.   The plaintiffs conclude that the judge's

failure to instruct on these points led the jury to find that

the defendants had acquired Doull's informed consent regarding

the progesterone cream.   Because the plaintiffs objected, we

review for prejudicial error.   See Blackstone v. Cashman, 448
Mass. 255, 270 (2007).    We conclude that the judge's

instructions were not erroneous.

     25Title 244 Code Mass. Regs. § 9.04(5) states: "Full
Disclosure. When proposing any diagnostic or therapeutic
intervention which is beyond the scope of generic nursing
practice, an [advanced practice nurse] shall fully disclose to
the patient or to the patient's representative the risks and
benefits of, and alternatives to, such intervention and shall
document such disclosure in the patient's record."
                                                                  34

     A.   Standard of care.   "To prevail on a claim of medical

malpractice, a plaintiff must establish the applicable standard

of care . . . ."   Palandjian v. Foster, 446 Mass. 100, 104

(2006).   "In Massachusetts, 'it is entirely proper to offer in

evidence . . . [an official regulation] to show the relevant

standard of care.'"   Campbell v. Cape & Islands Healthcare

Servs., Inc., 81 Mass. App. Ct. 252, 255 (2012), quoting Herson

v. New Boston Garden Corp., 40 Mass. App. Ct. 779, 793 (1996).

See Mass. G. Evid. § 414 (2020) ("Safety rules, governmental

regulations or ordinances, and industry standards may be offered

by either party in civil cases as evidence of the appropriate

care under the circumstances").    However, a judge need not

instruct on a regulation if it is "not relevant to the facts of

[the] case."   Boothby v. Texon, Inc., 414 Mass. 468, 483, 484

(1993) ("A judge need not instruct the jury on every spin th at a

party can put on the facts").

     Focusing on what was disputed here regarding the informed

consent claims resolves the plaintiffs' issue with the adequacy

of the standard of care instructions.   At trial, it was

undisputed that the defendants owed Doull a duty to inform her

about the material risks of, and alternatives to, the
                                                                    35

progesterone cream.26   The parties disputed what constituted a

material risk of the treatment, with each side putting forth

conflicting expert testimony on whether natural progesterone

cream applied topically would increase the chances of developing

blood clots.   It is unclear how further instruction on 244 Code

Mass. Regs. § 9.04(5), which speaks only generally of the duty

to inform, could have aided the jury in establishing the

progesterone cream's material risks.27   To establish these,

jurors would have had to look to expert testimony -- exactly

what the judge instructed them to do.    Therefore, the standard

of care instructions did not prejudice the plaintiffs.

     B.   Breach.   The plaintiffs' argument that the trial judge

erroneously failed to instruct the jury that breach could be

established through a defendant's admission is equally without

     26In fact, the judge instructed the jury that "a medical
care provider owes to his or her patient the duty to disclose,
in a reasonable manner, all significant medical information that
the medical care provider possesses or reasonably should
possess[] that is material to an intelligent decision by the
patient whether to undergo a proposed course of treatment."
     27The plaintiffs also, somewhat obliquely, point to other
policies and procedures offered in evidence as sources of the
standard of care, alleging that these, too, were improperly
overshadowed by expert testimony in the instruction. Because
the judge told the jurors to examine all of the evidence entered
during the trial when determining the standard of care, it is
unclear how the instructions were improper, let alone
prejudicial.
                                                                   36

merit.28   "Testimony concerning conclusory admissions by a

malpractice defendant may suffice to sustain a jury's finding of

negligence if, from the admission, the jury 'could infer an

acknowledgment of all the necessary elements of legal

liability.'"   Collins v. Baron, 392 Mass. 565, 568 (1984),

quoting Zimmerman v. Litvich, 297 Mass. 91, 94 (1937).     Indeed,

we have said that "a doctor's admission that an injury was 'his

fault' sufficed to warrant a jury's finding of negligence.     See

Collins, supra, citing Tully v. Mandell, 269 Mass. 307, 308-309

(1929).    No such admission, however, is at issue here.

     During her testimony at trial, Foster admitted that she did

not inform Doull that natural progesterone cream carried any

risk of blood clotting.    Yet, this admission would not have been

sufficient to render Foster liable for failing to acquire

informed consent from Doull:    the jury would have had to find

that natural progesterone cream carried a risk of causing blood

clots in order for Foster to have committed a breach of her duty

to inform Doull about the risk.    Cf. Collins, 392 Mass. at 566

(defendant admitted that he "made a mistake during the

     28The plaintiffs' argument on this point is difficult to
follow. They claim that the "erroneous instruction also spread
to the breach portion of the case, again with overemphasis on
experts." This is followed by discussion of Foster's admission
discussed infra. Consequently, we interpret this argument as a
claim that the judge ought to have instructed the jury that
Foster's admissions could establish breach.
                                                                    37

hysterectomy," had severed plaintiff's ureter, and was at

fault).    Whether the progesterone cream posed such a risk was a

matter that the jury would have had to turn to the experts'

testimony to determine.       The jury instructions on breach, then,

were proper.

     b.    Motion to amend.    The plaintiffs contend that their

motion to amend the complaint to add WIC as a defendant should

have been allowed.    The judge denied the plaintiffs' motion on

the grounds that the discovery deadline had passed and the

plaintiffs had failed to explain why they had not added WIC

earlier.

     "We review the denial of a motion to amend the complaint

for abuse of discretion."      Dzung Duy Nguyen v. Massachusetts

Inst. of Tech., 479 Mass. 436, 461 (2018).      Despite this

standard, "leave should be granted unless there are good reasons

for denying the motion."      Mathis v. Massachusetts Elec. Co., 409
Mass. 256, 264 (1991).     See Mass. R. Civ. P. 15 (a), 365 Mass.
761 (1974).    "Such reasons include 'undue delay, bad faith or

dilatory motive on the part of the movant, repeated failure to

cure deficiencies by amendments previously allowed, undue

prejudice to the opposing party by virtue of allowance of the

amendment, [and] futility of the amendment . . . .'"      Mathis,

supra, quoting Castellucci v. United States Fid. & Guar. Co.,

372 Mass. 288, 290 (1977).
                                                                   38

     The plaintiffs claim to have learned in November 2016 that

the defendants had ordered from WIC the progesterone cream that

Foster prescribed to Doull.   The plaintiffs did not move to add

WIC as a party until April 2017, approximately five months after

making the discovery and four months before trial began.     At the

time of their motion, the plaintiffs failed to explain the delay

or address that the discovery period had expired.    Given these

facts, the judge's denial of the plaintiffs' motion was not an

abuse of discretion.   See Mathis, 409 Mass. at 264-265 ("an

unexcused delay in seeking to amend is a valid basis for denial

of a motion to amend"); Castellucci, 372 Mass. at 292 ("When

trial is as imminent as it was in this case, a judge may give

weight to the public interest in the efficient operation of the

trial list and to the interests of other parties who are ready

for trial").

     c.   Posttrial contact with jurors.   The plaintiffs argue

that the trial judge improperly granted the defendants' motion

to require judicial approval for postverdict contact with the

jurors.   Considering the reasons for the plaintiffs' request to

initiate contact with the jurors, the judge's decision was

proper.

     Attorneys are generally not required to seek court approval

before initiating postverdict contact with the jury.   See

Commonwealth v. Moore, 474 Mass. 541, 551 (2016).   An attorney
                                                                  39

may not, however, initiate postverdict contact with the jury if

"the communication is prohibited by law or court order"

(emphasis added).   Mass. R. Prof. C. 3.5 (c) (1), as appearing

in 471 Mass. 1428 (2015).   See Moore, supra at 549 n.10 ("We do

not question that, when appropriate, a judge in a particular

case may restrict or even prohibit attorneys' unsupervised

communication with jurors postverdict; such a court order is

expressly contemplated by rule 3.5 [c] [1]").   A judge may bar

postverdict contact with the jury if the attorney seeks to

inquire "into the contents of jury deliberations and thought

processes of jurors." Id. at 548.

     In response to the defendants' motion to require judicial

approval for postverdict contact with the jurors, the plaintiffs

explained that they sought to contact the jurors in order to ask

them "how they felt about [Miller's trial counsel] nearly

assaulting Dr. Genecin . . . on the witness stand and if they

would have felt differently if the attorney was male and witness

was female."29   These objectives fall far afield of anything

resembling a valid reason for approaching jurors and instead

appear to be aimed at "inquiry into the contents of jury

deliberations and thought processes of jurors and the

     29In granting the defendants' motion, the trial judge noted
that no assault occurred and that the plaintiffs' suggestion
otherwise could distort the jurors' understanding of the
advocacy process.
                                                                    40

impeachment of jury verdicts based on information that might be

gained from such inquiry."     See Moore, 474 Mass. at 548.   For

these reasons, the trial judge's concerns that the plaintiffs

would pry into the jurors' deliberations were warranted and the

prohibition on postverdict contact with the jury was

appropriate.

     d.   Additional claims.   Finally, the plaintiffs make a

litany of arguments that cite few or no legal authorities,

contain cursory or no argumentation, or are unsubstantiated in

the record or reference no portions of the record at all.30

     30The plaintiffs contend, for example, that if the trial
judge had admitted every publication they offered in evidence,
then "a different result on the informed consent questions would
have been likely." For this conclusion, the plaintiffs cite
once to Pfeiffer v. Salas, 360 Mass. 93, 99 (1971), but provide
no discussion of it. We further discern no abuse of discretion
in the trial judge's limitations on the use and reference to
certain drugs containing progesterone that were not demonstrated
to be the same as or sufficiently similar to the topical
progesterone cream used by Doull. Next, the plaintiffs make at
least nine different versions of the argument that the judge
systematically abused her discretion and deprived them of a fair
and balanced trial. For each iteration of this claim, the
plaintiffs fail to explain how the judge abused her discretion
or how it prejudiced them, resorting instead to vague
declarations that they were denied a fair trial. The plaintiffs
then turn to the judge's denial of their motion for judgment
notwithstanding the verdict on the defendants' affirmative
defenses. For this claim, the plaintiffs make no argument on
appeal at all, instead directing our attention to arguments they
made below. Finally, the plaintiffs argue that the judge abused
her discretion in various ways during the pretrial and discovery
processes. Again, these claims are made with scant argument.
More is required from appellate advocates.
                                                                   2

These claims do not rise to the level of appellate argument.31

See Mass. R. A. P. 16 (a) (9), as amended, 428 Mass. 1603

(1999).   We therefore do not consider them.32

     3.   Conclusion.   For the foregoing reasons, we affirm the

judgment and the order denying the plaintiffs' motion for a new

trial.

                                    So ordered.

     31Because the plaintiffs' appeal raised nonfrivolous
issues, we reject the defendants' call to award appellate
attorney's fees and double costs. See Masterpiece Kitchen &
Bath, Inc. v. Gordon, 425 Mass. 325, 330 n.11 (1997) ("The
determination whether an appeal is frivolous is left to the
sound discretion of the appellate court . . ."). See also Avery
v. Steele, 414 Mass. 450, 455 (1993), quoting Allen v.
Batchelder, 17 Mass. App. Ct. 453, 458 (1984) ("An appeal is
frivolous '[w]hen the law is well settled, when there can be no
reasonable expectation of a reversal'").

     32We cannot, however, pass over in silence the many
references made in the plaintiffs' brief to the trial judge's
supposed biases. At various points, the plaintiffs' counsel
insinuates or outright alleges that the trial judge was biased
toward the defendants. Indeed, the plaintiffs' brief conclu des
by noting of the causation issue: "The simple truth is the
Trial Court gave the wrong instruction of law in order to
guarantee a defense verdict." We have reviewed the transcript,
and the judge exhibited patience, rectitude, and fairness
throughout the trial. The record supports none of the
accusations found in the plaintiffs' briefs.
     LOWY, J. (concurring, with whom Gaziano, J., joins).       Today

the court abandons decades of precedent in an attempt to clarify

confusion that does not exist.     Abandoning the substantial

contributing factor instruction in circumstances where there is

more than one legal cause of an injury will, in my view, inure

to the detriment of plaintiffs with legitimate causes of action

while not clarifying the existing law of causation.     To be

clear, I agree that regardless of the test, the outcome in this

case is the same.     Here, the jury found only one breach on which

to consider causation; this is the paradigmatic situation for

but-for causation.1    Yet for the following reasons, I would

maintain the current practice of applying the substantial

contributing factor test to multiple cause cases.

     1.   Current law.    We have long applied the substantial

contributing factor test.     See, e.g., Bernier v. Boston Edison

Co., 380 Mass. 372, 386 (1980); Tritsch v. Boston Edison Co.,

     1 At trial, plaintiffs argued three theories of negligence:
(1) that Anna C. Foster and Richard J. Miller failed to acquire
informed consent from Laura Doull, (2) that Foster failed to
diagnose Doull properly during her spring 2011 visits, and (3)
that Miller was negligent in his supervision of Foster. The
jury eliminated informed consent as a possible theory, thus
leaving only the failure to diagnose and the negligent
supervision claims. These two theories of negligence shared
only one cause, because finding liability on the negligent
supervision claim hinged on the failure to diagnose claim.
Thus, although the judge should have initially instructed on the
substantial contributing factor test, failure to do so was
harmless.
                                                                    2

363 Mass. 179, 182 (1973); Falvey v. Hamelburg, 347 Mass. 430,

435 (1964); Quinby v. Boston & Me. R.R., 318 Mass. 438, 444-445

(1945); Vigneault v. Dr. Hewson Dental Co., 300 Mass. 223, 229

(1938).   References in our cases to causes being "substantial

contributing" factors even predate the test's modern formulation

in the Restatement of Torts (1939) and Restatement (Second) of

Torts (1965).   See Wheeler v. Worcester, 10 Allen 591, 594, 597

(1865).   In recent years, we have refined how the test is

applied to cause-in-fact problems.   See Matsuyama v. Birnbaum,

452 Mass. 1, 30-31 (2008) (limiting substantial contributing

factor test to cases with multiple causes).    Examination of the

test reveals why it has so long endured.

     To begin, note how the substantial contributing factor test

mirrors the analysis of but-for causation.    Save for the rare

instances where two or more causes are each alone sufficient to

produce a result, we have made clear that a substantial

contributing factor must actually make a difference as to

whether an event occurs in order to be considered a cause of it.

In O'Connor v. Raymark Indus., Inc., 401 Mass. 586, 592 (1988),

for example, we held that a jury must "distinguish between a

'substantial factor,' tending along with other factors to

produce the plaintiff's [harm], and a negligible factor, so

slight or so tangential to the harm caused that, even when

combined with other factors, it could not reasonably be said to
                                                                   3

have contributed to the result."   If the plaintiff cannot

demonstrate that the defendant's negligence substantially

contributed to the alleged harm, then the defendant cannot be

held liable.   See id. at 587.   Just as but-for causation does,

the substantial contributing factor test embodies a core

principle of tort law:   only those who meaningfully contributed

to a person's harm should be liable for it.2   See Wainwright v.

Jackson, 291 Mass. 100, 102 (1935).

     2 Semantics further proves the point. A substantial
contributing factor must first and foremost be a genuine factor.
It would be difficult to contemplate how conduct could
"substantially" contribute to an outcome and yet the outcome
would have happened without the conduct. See Black's Law
Dictionary 1728 (11th ed. 2019) (defining "substantial" as "1.
Of, relating to, or involving substance; material . . . . 2.
Real and not imaginary; having actual, not fictitious, existence
. . . . 3. Important, essential, and material; of real worth
and importance").

     Other courts have echoed this sentiment. See, e.g., June
v. Union Carbide Corp., 577 F.3d 1234, 1239 (10th Cir. 2009)
("the ultimate legal standards in the two Restatements," one of
which advocates substantial contributing factor and other of
which advocates but-for cause, "are essentially identical");
Mitchell v. Gonzales, 54 Cal. 3d 1041, 1052 (1991) ("the
'substantial factor' test subsumes the 'but for' test");
Burnette v. Eubanks, 308 Kan. 838, 850-851 (2018) ("An act of
negligence which contributes to an accident must, of necessity,
have at least a part in causing the accident" [citation
omitted]). Hence, even critics of the substantial contributing
factor test concede that it works fine when clearly delineated:
the test implicitly subsumes within it the same requirements of
but-for cause. See Robertson, The Common Sense of Cause in
Fact, 75 Tex. L. Rev. 1765, 1781 (1997) ("As long as courts are
careful to explain that they are not adding a sixth requirement
-- but instead are either using the 'substantial factor' test
for cause in fact in lieu of the but-for approach or are using
                                                                     4

     Where the two tests part ways is in where they focus

jurors' attention.     The substantial contributing factor test is

positive in outlook:    it frames causation to have a juror start

by considering what actually happened, and whether the

defendant's actions played a part in producing the result.    See

Restatement (Second) of Torts § 431(a).     But-for causation, on

the other hand, begins not with what was, but with what might

have been:   in order to determine whether what occurred was the

product of the defendant's action, the jury must determine how

the sequence of events would have played out in the absence of

this conduct.   See Restatement (Third) of Torts:    Liability for

Physical and Emotional Harm § 26 comment e (2010) (Restatement

[Third] of Torts).

     Although this counterfactual framing may be straightforward

when the jury are considering only one theory of causation, I

fear that in cases with multiple causes it invites the jury to

get caught up in speculative combinations of "what if" and "if

only."   See, e.g., Green, The Causal Relation Issue in

Negligence Law, 60 Mich. L. Rev. 543, 556 (1962) ("Tests of this

character have the same vice as any 'if,' or any analogy.    They

take the eye off the ball").    See also Spellman & Kincannon, The

Relation Between Counterfactual ("But For") and Causal

the 'substantial factor' vocabulary to describe a general
approach to the legal cause issue -- no clear harm is done").
                                                                      5

Reasoning:     Experimental Findings and Implications for Jurors'

Decisions, 64 Law & Contemp. Probs. 241, 243-247 (2001)

(detailing how moral and other nonfactual factors enter into

jurors' considerations when engaged in counterfactual

reasoning).    The substantial contributing factor test better

replicates how many people understand causation and thus avoids

this issue.

     These considerations reveal not only why we recently said

that the substantial contributing cause test was "useful" in

cases with multiple causes, but also how the test promotes

fairness.     Matsuyama, 452 Mass. at 30.   As with the other

elements of a negligence claim, plaintiffs bear the burden of

proving causation.     See Glidden v. Maglio, 430 Mass. 694, 696

(2000).     In the sorts of byzantine fact patterns that often

arise in medical malpractice, toxic tort, and other tort cases

with multiple causes, an instruction on but-for causation

provides defendants with tools unavailable to plaintiffs.       For

example, civil defendants in cases with multiple causes

sometimes "employ an 'empty chair' defense -- blaming the party

not on trial."     Lind v. Domino's Pizza LLC, 87 Mass. App. Ct.
650, 665 (2015).     This strategy is but one example of how but -

for causation encourages jurors to speculate about alternative

realities.     An instruction on the substantial contributing

factor test, however, focuses the jurors attention directly on
                                                                     6

what ought to determine legal responsibility:    the conduct of

the parties.

     2.    The court's approach.   The court abandons what has been

our steady and successful practice of applying the substantial

contributing factor test in torts cases involving all sorts of

fact patterns, not just in "twin fire" and toxic tort cases.

See, e.g., Renzi v. Paredes, 452 Mass. 38, 44 n.10 (2008)

(substantial contributing factor test proper in loss of chance

case where liability was premised on failure to diagnose); Morea

v. Cosco, Inc., 422 Mass. 601, 603 n.2 (1996) (jury found

defective product design not "substantial cause" of child's

death); Michnik-Zilberman v. Gordon's Liquor, Inc., 390 Mass. 6,

14 (1983) (jury could find liquor store's sale of alcohol to

minor was "substantial legal factor" causing cyclist's death) ;

Mullins v. Pine Manor College, 389 Mass. 47, 58, 62 (1983) (jury

could find that injury to rape victim was substantially caused

by college's negligent security).

     Why the sudden about-face?     Precedent does not dictate the

new direction, as recent affirmations of the substantial

contributing factor test attest.    See, e.g., Renzi, 452 Mass. at

44 n.10.    Practices, too, remain unaltered.   See, e.g., Parsons

v. Ameri, 97 Mass. App. Ct. 96, 102 (2020) (jury instructed on

substantial contributing factor test in medical malpractice

case).    Indeed, even the current Massachusetts Continuing Legal
                                                                  7

Education Civil Practice Jury Instructions recognize our use of

the substantial contributing factor test in cases with multiple

causes.   See Massachusetts Superior Court Civil Practice Jury

Instructions § 4.3.4(a) practice note (3d ed. 2014) (but-for

test is "suitable for use in the ordinary tort case without the

complexity of multiple causes or tortfeasors").

     Only one thing has changed:   the Restatements.   Whereas

earlier Restatements embraced the substantial contributing

factor test, the Restatement (Third) of Torts has rejected it.

Compare Restatement of Torts § 431(a) and Restatement (Second)

of Torts § 431(a), with Restatement (Third) of Torts § 26.

Specifically, the Restatement (Third) calls the substantial

contributing factor test "confusing," concluding that, aside

from multiple sufficient cause cases, the test "provides nothing

of use in determining whether factual cause exists."

Restatement (Third) of Torts § 26 comment j.   This position is

now the court's.   What we very recently called "useful" is now

supposedly no longer so.   See Matsuyama, 452 Mass. at 30.

     Of course, we are not bound to follow old law when new

facts reveal that application is unworkable in our jurisdiction.

See Franklin v. Albert, 381 Mass. 611, 617 (1980).     Yet such

facts are absent here.   Notably, when the court discusses the

confusion that the substantial contributing factor test has
                                                                     8

allegedly generated, citations to our cases drop off. 3   Instead,

the court replicates an abstract and academic discussion of the

problems that the Restatement (Third) of Torts found with the

standard.4   See ante at   -   .    We should be "disinclined to

fix something that is not broken, even if [we] would have

constructed it differently in the first place." 5   Stonehill

College v. Massachusetts Comm'n Against Discrimination, 441
Mass. 549, 589 (Sosman, J., concurring), cert. denied sub nom.

Wilfert Bros. Realty Co. v. Massachusetts Comm'n Against

Discrimination, 543 U.S. 979 (2004).

     Furthermore, how much of the apparent confusion the court's

solution would dispel is unclear.    Although the court criticizes

the substantial contributing factor test for requiring judges to

     3 One of the court's citations to our cases is also
inaccurate. Matsuyama, 452 Mass. at 30, is a loss of chance
medical malpractice case; it is neither a toxic tort nor an
asbestos case, although the court lumps it in with those cases.
     4 By way of explanation, the Restatement (Third) of Torts
catalogues various uses of the test across different
jurisdictions. The test appears to be more confusing when
comparing cases across jurisdictions -- which unsurprisingly
evince the sort of pluralism characteristic of the common law's
development -- than when comparing cases within a jurisdiction.
Regardless, absent from these comparisons is Massachusetts. See
Restatement (Third) of Torts § 26 comment j.
     5 Other States have also successfully continued to apply the
substantial contributing factor test in recent years despite the
alternative presented by the Restatement (Third) of Torts. See,
e.g., O'Grady v. State, 140 Haw. 36, 46 (2017) (reaffirming use
of test in negligence cases).
                                                                          9

determine how many causes are alleged in a case, the court

provides not one standard of factual causation but many.       First,

there is basic but-for:   as is currently the practice, in cases

where there is one alleged cause, jurors should be instructed on

but-for causation.   See ante at    -     .    Second, there is but-

for plus:   in cases where there are more than one alleged cause,

it is "appropriate" to also inform the jurors that there can be

more than one but-for cause of a harm.6       See id. at note 12.

Third, there is the new instruction on the twin fires example:

in cases where there are multiple sufficient causes, jurors are

to be given a hypothetical scenario detailing a camping trip

gone wrong, told that "[a] defendant whose tortious act was

fully capable of causing the plaintiff's harm should not escape

liability merely because of the happenstance of another

sufficient cause, like the second fire, operating at the same

time" along with a follow-up explanation of this instruction,

and then sent to deliberate.   See id. at        .   Fourth, and

finally, the substantial contributing factor test remains:          for

all its purported confusion, the standard continues to work well

in toxic tort cases -- except for the fact that the court also

     6 Even but-for plus presents an option within an option, as
the court implies by noting that it is merely "appropriate," not
necessary, for the trial judge to so instruct the jury in cases
where there are multiple alleged causes.
                                                                   10

invites in a footnote overturning what it otherwise praises. 7

See id. at note 21.

     The Restatements are owed respect.   Our cases, however,

deserve more.   See Mabardy v. McHugh, 202 Mass. 148, 152 (1909)

("Parties should not be encouraged to seek re-examination of

determined principles and speculate on a fluctuation of the law

with every change in the expounders of it").    The number of

tests the court provides is a tacit recognition of what our

cases have long understood:    the but-for standard is useful, but

limited in its usefulness.    Given that our cases have had

decades to refine this point, following them is the prudent

course.

     7 Additionally, adopting a new approach to cause-in-fact
issues in torts will encourage litigants to press for its
application in other areas of the law beyond negligence, such as
commercial disparagement, defamation, and false representation.
See, e.g., HipSaver, Inc. v. Kiel, 464 Mass. 517, 537 (2013),
quoting Restatement (Second) of Torts § 633 comment g ("[w]hen
the loss of a specific sale is relied on to establish pecuniary
loss, it must be proved that the publication was a substantial
factor influencing the specific, identified purchaser in his
decision not to buy"); Murphy v. Boston Herald, Inc., 449 Mass.
42, 67 (2007) ("The judge properly instructed the jury: 'The
pain and suffering for which [the plaintiff] is entitle d to
recover in this action is the pain and suffering which the
defamatory statement was, or were, a substantial factor in
producing'" [alteration in original]); Reisman v. KPMG Peat
Marwick LLP, 57 Mass. App. Ct. 100, 112 (2003) ("It has long
been the law in Massachusetts that, where reliance on a
fraudulent misstatement is a substantial factor in the decision
to purchase and/or retain stock, the maker of a false
representation is liable for a subsequent loss in the value of
stock suffered in reliance on the false representation").
                                                                  11

     3.   Conclusion.   With so many pages of the Massachusetts

Reports already filled with the successful application of the

substantial contributing factor test, the court's conclusion

that the test is now unworkable defies experience and unravels

precedent.   I fear that it does so at the price of fairness.