Case Title: Commonwealth v. Gerhardt

Citation: 

Docket Number: SJC-11967

State: massachusetts

Court: Massachusetts Supreme Court

Date: 2017-09-19T00:00:00Z

Document:
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SJC-11967 
 
COMMONWEALTH  vs.  THOMAS J. GERHARDT. 
 
Worcester.     January 6, 2017. - September 19, 2017. 
 
Present:  Gants, C.J., Lenk, Hines, Gaziano, Lowy, & Budd, JJ.1 
 
 
Marijuana.  Motor Vehicle, Operating under the influence.  
Evidence, Field sobriety test. 
 
 
 
 
Complaint received and sworn to in the Worcester Division 
of the District Court Department on April 24, 2013. 
 
 
A motion for a hearing to challenge the admissibility of 
certain evidence was heard by Andrew M. D'Angelo, J., and 
questions of law were reported by him to the Appeals Court. 
 
 
The Supreme Judicial Court granted an application for 
direct appellate review. 
 
 
 
Rebecca A. Jacobstein, Committee for Public Counsel 
Services, for the defendant. 
 
Michelle R. King, Assistant District Attorney, for the 
Commonwealth. 
 
Steven S. Epstein & Marvin Cable, for National Organization 
for the Reform of Marijuana Laws, amicus curiae, submitted a 
brief. 
 
Michael A. Delsignore & Julie Gaudreau, for National 
College for DUI Defense, amicus curiae, submitted a brief. 
 
 
                                                          
 
 
1 Justice Hines participated in the deliberation on this 
case prior to her retirement. 
2 
 
 
GAZIANO, J.  In this case we are asked to consider the 
admissibility of field sobriety tests (FSTs) where a police 
officer suspects that a driver has been operating under the 
influence of marijuana.  Police typically administer three 
FSTs -- the "horizontal gaze nystagmus test," the "walk and turn 
test" and the "one leg stand test" -- during a motor vehicle 
stop in order to assess motorists suspected of operating under 
the influence of alcohol or other drugs.  These tests were 
developed specifically to measure alcohol consumption, and there 
is wide-spread scientific agreement on the existence of a strong 
correlation between unsatisfactory performance and a blood 
alcohol level of at least .08%. 
 
By contrast, in considering whether a driver is operating 
under the influence of marijuana, there is as yet no scientific 
agreement on whether, and, if so, to what extent, these types of 
tests are indicative of marijuana intoxication.  The research on 
the efficacy of FSTs to measure marijuana impairment has 
produced highly disparate results.  Some studies have shown no 
correlation between inadequate performance on FSTs and the 
consumption of marijuana; other studies have shown some 
correlation with certain FSTs, but not with others; and yet 
other studies have shown a correlation with all of the most 
frequently used FSTs.  In addition, other research indicates 
3 
 
that less frequently used FSTs in the context of alcohol 
consumption may be better measures of marijuana intoxication. 
 
The lack of scientific consensus regarding the use of 
standard FSTs in attempting to evaluate marijuana intoxication 
does not mean, however, that FSTs have no probative value beyond 
alcohol intoxication.  We conclude that, to the extent that they 
are relevant to establish a driver's balance, coordination, 
mental acuity, and other skills required to safely operate a 
motor vehicle, FSTs are admissible at trial as observations of 
the police officer conducting the assessment.  The introduction 
in evidence of the officer's observations of what will be 
described as "roadside assessments" shall be without any 
statement as to whether the driver's performance would have been 
deemed a "pass" or a "fail," or whether the performance 
indicated impairment.  Because the effects of marijuana may vary 
greatly from one individual to another, and those effects are as 
yet not commonly known, neither a police officer nor a lay 
witness who has not been qualified as an expert may offer an 
opinion as to whether a driver was under the influence of 
marijuana.2 
 
1.  Background.  a.  Prior proceedings.  Following a motor 
vehicle stop, Thomas Gerhardt was charged in the District Court 
                                                          
 
2 We acknowledge the amicus briefs in support of the 
defendant submitted by the National College for DUI Defense and 
the National Organization for the Reform of Marijuana Laws. 
4 
 
with operating a motor vehicle under the influence of marijuana, 
in violation of G. L. c. 90, § 24.  Gerhardt filed a motion for 
a Daubert-Lanigan hearing, seeking to challenge the 
admissibility of evidence concerning his performance on FSTs 
conducted after the stop.  See Daubert v. Merrell Dow Pharms., 
Inc., 509 U.S. 579, 592-595 (1993); Commonwealth v. Lanigan, 419 
Mass. 15, 24-27 (1994).  After an evidentiary hearing, a 
District Court judge reported four questions to the Appeals 
Court, pursuant to Mass. R. Crim. P. 34, as amended, 442 Mass. 
1501 (2004). 
 
"1.  Whether police officers may testify to the 
administration and results of standard [FSTs] in 
prosecutions for [o]perating [u]nder the [i]nfluence of 
[m]arijuana as they do in [o]perating [u]nder the 
[i]nfluence of [a]lcohol prosecutions? 
 
 
"2.  Are the effects of marijuana consumption 
sufficiently within the common knowledge and experience of 
a lay person, such that a non-expert witness may offer 
opinion evidence whether a person is 'high' on marijuana? 
 
 
"3.  May a police officer, who has not been qualified 
as an expert witness, testify to the effects of marijuana 
on a person such as bloodshot eyes, lack of coordination 
and/or balance, reaction times, slow speech, paranoia, or 
relaxed responses[?] 
 
 
"4.  May a juror rely on their own experience and 
common sense about the effects of marijuana as they may do 
in an [o]perating [u]nder the [i]nfluence of [a]lcohol 
prosecution?"  [footnote omitted]. 
 
We granted Gerhardt's application for direct appellate 
review.  After oral argument, we remanded the matter to the 
District Court judge who had reported the questions for further 
5 
 
findings on eleven specific issues.  Following the return of the 
judge's findings, we again heard oral argument in the matter. 
 
b.  Facts.  The parties submitted a statement of agreed 
facts as to the evidence that the Commonwealth would seek to 
present at trial.  On February 13, 2013, at approximately 
12:20 A.M., Trooper French of the State police3 observed a blue 
Suzuki Grand Vitara motor vehicle traveling south on Route 146, 
without the rear lights on.  French followed the vehicle as it 
left Route 146 at exit 8.  He activated his emergency lights and 
stopped the vehicle on Elmwood Street in Millbury. 
 
French approached the vehicle on the passenger side.  There 
were three occupants in the vehicle:  the driver, later learned 
to be Gerhardt, and two passengers.  French saw smoke inside the 
vehicle, and, as soon as the front passenger window was lowered, 
he detected "the distinct odor of burnt marijuana."  He also saw 
a large amount of what he identified as cigar tobacco on the 
floor, and a cigar slicer on the key ring in the ignition.  The 
trooper asked the driver for his driver's license and 
registration.  Gerhardt handed him the license and said that he 
did not have his registration. 
 
French asked Gerhardt how much marijuana was in the 
vehicle.  Gerhardt responded that there were "a couple of 
roaches" in the ashtray; he pulled two largely-consumed rolled 
                                                          
 
3 Trooper French's first name is not apparent in the record. 
6 
 
cigarettes from the ashtray and handed them to French.  French 
then asked when the occupants had smoked marijuana.  One of the 
passengers responded that they had smoked about twenty minutes 
previously.  Gerhardt said that it had been about three hours 
earlier.  French walked to the driver's side of the vehicle and 
noticed that the light switch was in the "off" position.  He 
asked Gerhardt how much he had smoked.  Gerhardt responded that 
he had smoked approximately one gram of marijuana. 
 
French then asked Gerhardt to step out of the vehicle to 
perform FSTs.  French administered a number of FSTs, including 
the horizontal gaze nystagmus test (HGN);4 the nine-step walk-
and-turn test (WAT); and the one-leg-stand test (OLS).  French 
also asked Gerhardt to recite the alphabet from D to Q and to 
count backward from seventy-five to sixty-two. 
 
Gerhardt had no nystagmus indicators, and was able to 
recite the requested portion of the alphabet and to count 
backwards.  He did not perform the WAT as instructed, even after 
                                                          
 
4 "Nystagmus is '[a]n abnormal and involuntary movement of 
the eyeballs from side to side or up and down, but usually from 
side to side.'"  Commonwealth v. Sands, 424 Mass. 184, 186 
(1997), quoting State v. Merritt, 36 Conn. App. 76, 84 (1994).  
An officer administers the HGN test by having the subject focus 
on a moving object and observing whether the subject is able to 
follow the object smoothly with his or her eyes, whether the 
subject's eyes bounce at the extremes of the field of vision, 
and whether they exhibit nystagmus, where there is an angle of 
less than forty-five degrees between the eyes and the object.  
Sands, supra at 186-187.  Introduction of the results of this 
test at trial requires expert testimony.  See id. at 188. 
7 
 
several explanations and a demonstration by the trooper in 
response to Gerhardt's first answer in the negative when asked 
whether he understood the instructions.  Rather than standing 
heel to toe, with his right foot in front and his left toes 
touching his heel, as he had been shown, Gerhardt moved his feet 
so that they were side by side; he also did not turn around as 
instructed.  French determined that "the results of this test 
indicated that Gerhardt was impaired."  The trooper then 
provided instructions and gave a demonstration of the OLS test, 
and Gerhard indicated that he understood.  In performing the 
test, however, Gerhard did not remain upright on one foot, 
instead putting his foot down multiple times, and swayed.  
French determined that "the results of this test indicated that 
Gerhardt was impaired." 
 
After administering these tests, French concluded that 
Gerhardt was under the influence of marijuana.  French informed 
Gerhardt that he was not under arrest, but had him sit in the 
back of French's cruiser.  Both passengers were asked to step 
out of the vehicle and were pat frisked.  They, too, were told 
that they were not under arrest, and were placed in the back 
seat of the cruiser.  A second trooper arrived at the scene.  
During a search of the vehicle, the troopers recovered two more 
marijuana "roaches" and a marijuana stem. 
8 
 
 
On April 24, 2013, a criminal complaint issued against 
Gerhardt charging him with operating a motor vehicle while under 
the influence of drugs, pursuant to G. L. c. 90, 
§ 24 (1) (a) (1), and traffic violations. 
 
2.  Discussion.  a.  Field sobriety tests.  The FSTs, which 
were designed to detect alcohol impairment, are administered and 
evaluated in a standardized manner.  The two tests primarily 
administered in the context of alcohol impairment are the WAT 
and the OLS, which are designed to assess an individual's 
balance, coordination, dexterity, ability to follow directions, 
and ability to focus attention on multiple subjects at the same 
time.5 
 
In performing the WAT, the subject is directed to take nine 
steps, walking heel-to-toe, along a real or imaginary straight 
line.  The subject then turns on one foot and returns in the 
same manner.  An officer administering the WAT looks for eight 
specific indicators of impairment:  losing balance while 
listening to the instructions, beginning before the instructions 
are finished, stopping to regain balance while walking, failing 
to walk heel-to-toe, stepping off the line, using arms to 
                                                          
 
 
5 There are a number of other FSTs, such as the "Romberg 
balance test," in which the subject stands with heels and toes 
together and arms at the side of the body and tips his or her 
head back slightly and estimates the passage of thirty seconds, 
and the "finger to nose test," which are less frequently used in 
the context of alcohol impairment. 
9 
 
balance, making an improper turn, or taking an incorrect number 
of steps.  Where the consumption of alcohol is at issue, there 
is an established correlation between performance on the test 
and blood alcohol content (BAC), with some research indicating 
that as many as seventy-nine per cent of individuals who exhibit 
two or more of these indicators have a BAC of 0.08 per cent or 
higher. 
 
In performing the OLS, the subject stands with one foot 
raised approximately six inches off the ground while counting 
aloud for thirty seconds.  An officer conducting the test looks 
for four indicators of impairment:  swaying while balancing, 
using arms to balance, hopping to maintain balance, and putting 
the foot down.  Research has indicated that as many as eighty-
three per cent of individuals who exhibit two or more of these 
indicators have a BAC of 0.08 per cent or higher. 
 
b.  Admissibility of the FSTs in the context of marijuana.  
While using marijuana is no longer a crime in Massachusetts for 
adults who are at least twenty-one years old,6 operating a motor 
vehicle while under the influence of marijuana remains a 
criminal offense.  See G. L. c. 90, § 24.  In a prosecution for 
operating while under the influence of marijuana, it is the 
Commonwealth's burden to prove beyond a reasonable doubt, in 
                                                          
 
6 See St 2016, c. 334, "The Regulation and Taxation of 
Marijuana Act." 
10 
 
addition to the other elements of the offense, that a 
defendant's consumption of marijuana impaired his or her ability 
to drive a motor vehicle safely.  See Commonwealth v. Daniel, 
464 Mass. 746, 756 (2013), quoting Commonwealth v. Connolly, 394 
Mass. 169, 173 (1985) (in prosecution for operating under 
influence of alcohol or marijuana, the Commonwealth "need not 
prove that the defendant actually drove in an unsafe or erratic 
manner, . . . [but] it must prove a diminished capacity to 
operate safely"). 
 
Unlike alcohol, marijuana does not act as a general central 
nervous system depressant, impairing functions throughout the 
body.  Nonetheless, the primary psychoactive substance in 
marijuana, tetrahydrocannibol (THC), is known to have an impact 
on several functions of the brain that are relevant to driving 
ability, including the capacity to divide one's attention and 
focus on several things at the same time, balance, and the speed 
of processing information.  While not all researchers agree, a 
significant amount of research has shown that consumption of 
marijuana can impair the ability to drive. 
There is ongoing 
disagreement among scientists, however, as to whether the FSTs 
are indicative of marijuana impairment.  In recent years, 
numerous studies have been conducted in an effort to determine 
whether a person's performance on the FSTs is a reliable 
11 
 
indicator of impairment by marijuana.7  These studies have 
produced mixed results.8  For example, researchers found that the 
FSTs were mildly sensitive to the effects of marijuana, with the 
OLS being the most sensitive.  That study, however, also 
indicated that the OLS produced numerous false positives.9  Other 
researchers found that the OLS was a somewhat more reliable 
indicator of marijuana impairment than the WAT.10  In a more 
recent study, by contrast, a different group of researchers 
found that the WAT was a better indicator of marijuana 
impairment than the OLS.11  Researchers conducting another study 
found that marijuana significantly impaired performance on the 
                                                          
 
7 The judge noted several of these studies in his findings 
on remand from this court.  In addition, both parties provided 
numerous such studies in the record, and one of the amici did as 
well. 
 
 
8 The number of studies in this field is vast; we cite only 
a few representative examples. 
 
9 Bosker, Theunissen, Conen, Kuypers, Jeffery, Walls, 
Kauert, Toennes, Moeller, & Ramaekers, A Placebo-Controlled 
Study to Assess Standardized Field Sobriety Tests Performance 
During Alcohol and Cannabis Intoxication in Heavy Cannabis Users 
and Accuracy of Point of Collection Devices for Detecting THC in 
Oral Fluid, 223 Psychopharmacology 439, 443-444 (2012) (Bosker). 
 
10 Papafotiou, Carter, & Stough, An Evaluation of the 
Sensitivity of the Standardized Field Sobriety Tests (SFSTs) to 
Detect Impairment Due to Marijuana Intoxication, 180 
Psychopharmacology 107, 113 (2005) (Papafotiou). 
 
11 Declues, Perez, & Figueroa, A 2-Year Study of Delta-9-
tetrahydrocannabinol Concentrations in Drivers:  Examining 
Driving and Field Sobriety Test Performance, 61 J. Forensic 
Sciences 1664, 1669 (2016). 
12 
 
HGN, the WAT, and the OLS.12  Other studies have shown no 
correlation between performance on the HGN and consumption of 
marijuana, even where the OLS or WAT showed some sensitivity to 
marijuana consumption,13 while others have found no correlation 
between the consumption of marijuana and any of these FSTs.14 
 
As a result of these varied results, some researchers have 
suggested development of another group of FSTs, combining the 
currently less-frequently used Romberg stand test and the nose-
touch test, see note 5, supra, with a to-be-developed test on 
pupil constriction,15 or adding a scoring factor of head 
movements or jerks to the standard FSTs.16  Other researchers are 
working on a tongue or cheek swab test that directly measures 
levels of THC shortly after consumption.17  It is clear from the 
above, as the judge stated in his findings on remand, that the 
scientific community has yet to reach a consensus on the 
                                                          
 
12 Papafotiou, supra at 111-113. 
 
 
13 Hartman, Richman, Hayes, & Heustis, Drug Recognition 
Expert (DRE) Examination Characteristics of Cannabis Impairment, 
92 Accident Analysis and Prevention 219, 226 (2016) (Hartman). 
 
 
14 See generally Neavyn, Blohm, Babu, & Bird, Medical 
Marijuana and Driving:  a Review, 10 J. Med. Toxicol. 269 
(2014); Jones, Donnelly, Swift, & Weatherburn, Driving Under the 
Influence of Cannabis:  The Problem and Potential 
Countermeasures, 87 Crime & Justice Bulletin 1 (2005). 
 
 
15 See Hartman, supra at 226. 
 
 
16 See Papafotiou, supra at 108. 
 
 
17 See Bosker, supra at 442, 445. 
13 
 
reliability of FSTs to assess whether a driver is under the 
influence of marijuana. 
 
The lack of scientific agreement, however, does not, by 
itself, resolve the question whether a driver's performance on 
an FST is relevant evidence in a trial on a charge of operating 
under the influence of marijuana.  " The relevance threshold for 
the admission of evidence is low.  'Evidence is relevant if it 
has a "rational tendency to prove an issue in the case,"'" 
Commonwealth v. Arroyo, 442 Mass. 135, 144 (2004), quoting 
Commonwealth v. LaCorte, 373 Mass. 700, 702 (1977), or to 
"render a 'desired inference more probable than it would be 
[otherwise],'"  Arroyo, supra, quoting Commonwealth v. 
Fayerweather, 406 Mass. 78, 83 (1989).  To be relevant, evidence 
"need not establish directly the proposition sought; it must 
only provide a link in the chain of proof."  Commonwealth v. 
Sicari, 434 Mass. 732, 750 (2001), cert. denied, 534 U.S. 1142 
(2002), quoting Commonwealth v. Yesilciman, 406 Mass. 736, 744 
(1990). 
 
The absence of scientific consensus regarding the use of 
standard FSTs in attempting to evaluate marijuana intoxication 
does not mean that they have no probative value.  A police 
officer makes numerous relevant observations in the course of an 
encounter with a possibly impaired driver.  There is no doubt 
that an officer may testify to his or her observations of, for 
14 
 
example, any erratic driving or moving violations that led to 
the initial stop; the driver's appearance and demeanor; the odor 
of fresh or burnt marijuana; and the driver's behavior on 
exiting the vehicle. 
 
In our view, certain of the FSTs also may provide 
information that is relevant to the question of a defendant's 
impairment, and a police officer may testify, as a lay witness, 
to his or her observations of the defendant's performance.  In 
particular, observations of the performance of the OLS and the 
WAT may be admissible as evidence of a defendant's balance, 
coordination, ability to retain and follow directions, and 
ability to perform tasks requiring divided attention, and the 
presence or absence of other skills necessary for the safe 
operation of a motor vehicle.18  We see no reason why an 
officer's observations of a defendant's behavior on being asked 
to walk a straight line or to stand on one foot should be 
                                                          
 
18 The HGN stands on a different footing from the FSTs that 
are directed to balance and coordination.  We previously have 
held that, in a prosecution for operating under the influence of 
alcohol, "the HGN test relies on an underlying scientific 
proposition and therefore expert testimony is required."  See 
Sands, 424 Mass. at 188.  In addition, "there must be a 
determination as to the qualification of the individual 
administering the HGN test and the appropriate procedure to be 
followed if the HGN test results are to be admitted at trial."  
Id.  We reached this result because the correlation between 
alcohol intoxication and nystagmus is not within the common 
experience of jurors.  Id.  In the context of marijuana, any 
correlation between nystagmus and intoxication is even further 
beyond jurors' common knowledge and experience. 
15 
 
excluded because the scientific community's understanding of 
precisely how this correlates with marijuana use is still 
evolving.  We are not persuaded, however, that the FSTs can be 
treated as scientific tests establishing impairment as a result 
of marijuana consumption.  The scientific community has not 
reached a consensus as to whether a defendant's performance on 
any combination of FSTs, or on any individual FST, is correlated 
with marijuana use or impairment. 
 
The unsettled state of the scientific research suggests 
that FST evidence neither should be treated as a definitive test 
of impairment nor excluded entirely from consideration by the 
finder of fact.  Cf. Commonwealth v. Thomas, 476 Mass. 451, 464 
(2017) (where there is no consensus that simultaneous display of 
photographs is inferior to sequential display, "the 
decision . . . is best left to law enforcement, and the choice 
will continue to bear on the weight of the identification, but 
not on its admissibility").  Moreover, that marijuana can cause 
impairment of skills necessary to driving, such as coordination, 
concentration, and the ability to divide one's attention among 
multiple tasks is within the common experience and knowledge of 
jurors.  A police officer testifying to a defendant's 
performance on these FSTs therefore need not be qualified as an 
expert, and such evidence may be admitted without satisfying the 
Daubert-Lanigan requirements.  A police officer may not suggest, 
16 
 
however, on direct examination that an individual's performance 
on an FST established that the individual was under the 
influence of marijuana.19  Likewise, an officer may not testify 
that a defendant "passed" or "failed" any FST, as this language 
improperly implies that the FST is a definitive test of 
marijuana use or impairment.20 
 
Indeed, the word "test" itself inadvertently may lend "an 
aura of scientific validity."  See United States v. Horn, 185 F. 
Supp. 2d 530, 559 (D. Md. 2002).  We recognize, nonetheless, 
that it is not practicable to eliminate the concept of testing 
entirely from trial testimony.  The FSTs are used as means to 
evaluate a defendant's ability to perform discrete tasks which 
are correlated to skills required to safely drive a vehicle.  
See Webster's New Universal Unabridged Dictionary 1951 (2003) 
(defining "test" as, inter alia, "a set of questions, problems, 
or the like, used as a means of evaluating the abilities, 
                                                          
 
19 Here, for example, a trooper testified at the motion 
hearing that "the results of the [WAT and OLS] indicated that 
Gerhardt was impaired."  This testimony would not be admissible 
at trial. 
  
20 On cross-examination, defense counsel may challenge a 
police officer's testimony concerning a defendant's performance 
of an FST or any portion of an FST.  See S.L. Jones, Drunk 
Driving Defense, §§ 3.33-3.48 (2016-2017 ed.).  See also id. at 
§§ 3.49-3.54.  We do not bar defense counsel from eliciting from 
the officer his or her subjective evaluation of the defendant's 
performance, but we stress that defense counsel makes this 
strategic decision at his or her own peril, and opens the door 
to redirect examination by the Commonwealth on the same topic. 
17 
 
aptitudes, skills, or performance of an individual or group; 
examination," and "a set of standardized questions, problems, or 
tasks designed to elicit responses for use in measuring the 
traits, capacities, or achievements of an individual").  An 
officer administering the WAT, for example, assesses a 
defendant's ability to take nine steps, walk heel-to-toe on a 
straight line, turn around, and return in the same manner.  In 
some sense, the officer thereby "tests" (measures, examines, 
evaluates, assesses, or, at a minimum, observes) the driver's 
physical balance and coordination, as well as his or her mental 
ability to understand and follow directions and to perform 
divided-attention tasks, albeit not in the same way that a 
chemist in a laboratory tests a sample for the presence of a 
particular substance.  In all circumstances, however, it must be 
made clear to the fact finder that the WAT, the OLS, and the 
other FSTs do not directly test marijuana impairment.  The FSTs 
are a means of evaluating a defendant's balance, coordination, 
and other skills specific to that test.  In addition, a witness 
testifying to the performance of FSTs in the context of 
marijuana intoxication should refer to a driver's performance on 
"roadside assessments," so as not to suggest that they function 
as scientific validation of a defendant's sobriety or 
intoxication. 
18 
 
 
We emphasize as well another consequence of the lack of 
consensus regarding the FSTs:  the fact that the FSTs cannot be 
treated as scientific "tests" of impairment means that evidence 
of performance on FSTs, alone, is not sufficient to support a 
finding that a defendant's ability to drive safely was impaired 
due to the consumption of marijuana, and the jury must be so 
instructed.21 
 
c.  Lay testimony on the effects of marijuana.  We also are 
asked whether a police officer may testify, without being 
qualified as an expert, to the effects of marijuana consumption 
and may offer an opinion that a defendant was intoxicated by 
marijuana.  We conclude that an officer may not do so. 
 
"A lay opinion . . . is admissible only where it is 
'(a) rationally based on the perception of the witness; 
(b) helpful to a clear understanding of the witness's testimony 
or the determination of a fact in issue; and (c) not based on 
scientific, technical, or other specialized knowledge.'"  
Commonwealth v. Canty, 466 Mass. 535, 541 (2013), quoting Mass. 
G. Evid. § 701 (2013).  In the alcohol context, "a lay [officer] 
. . . may offer his opinion regarding a defendant's level of 
sobriety or intoxication but may not opine whether a defendant 
operated a motor vehicle while under the influence of alcohol or 
                                                          
 
21 A model jury instruction regarding FSTs, to be used in 
prosecutions for operating under the influence of marijuana, is 
set forth in the Appendix. 
19 
 
whether the defendant's consumption of alcohol diminished his 
ability to operate a motor vehicle safely."  Canty, supra at 
544, citing Commonwealth v. Jones, 464 Mass. 16, 17 n.1 (2012).  
Such lay opinion testimony is proper because it is not based on 
scientific, technical, or other specialized knowledge that would 
require expert testimony, but, rather, lies within the realm of 
common experience.  We long have observed that "[t]he 'effects 
of liquor upon the minds and actions of men are well known to 
everybody.'"  Commonwealth v. Wall, 469 Mass. 652, 671 (2014), 
quoting Commonwealth v. Taylor, 263 Mass. 356, 362 (1928).  See 
Canty, supra at 542, quoting Holton v. Boston Elevated Ry. Co., 
303 Mass. 242, 246 (1939) ("'the principal objective symptoms 
[of alcohol intoxication] are so well known' that we consider 
the lay opinion to have probative value"). 
 
No such general knowledge exists, however, as to the 
physical or mental effects of marijuana consumption, which vary 
greatly amongst individuals.  On remand, the District Court 
judge reported in his findings of fact, based on expert 
testimony presented by both sides and numerous scientific 
studies, as well as existing case law in Massachusetts, that 
"[n]o studies have concluded that any specific characteristics 
are routinely found in people who have used marijuana and were 
impaired.  Manifestations of impairment may differ between 
subjects who are under the influence of liquor and those who are 
20 
 
under the influence of marijuana, depressants, or stimulant 
substances.  The judge found further that some scientific 
studies had identified "four prevalent physical characteristics 
common among those who were determined to be cannabis-positive 
drivers . . . These physical characteristics are red and/or 
bloodshot eyes, a lack of convergence, eyelid tremors, and 
drowsiness."  He determined, however, that no testimony admitted 
at the Daubert-Lanigan hearing related these physical 
characteristics "to an inference of impaired driving by reason 
of marijuana use.  Further, no scientific studies validating 
these specific physical characteristics as symptomatic of 
impaired driving by reason of marijuana use were entered into 
evidence."  Our review of the record confirms that the judge’s 
findings regarding lay opinion evidence are supported by the 
documentary evidence and in the studies submitted to us. 
 
Where there is no scientific consensus on what, if any, 
physical characteristics indicate marijuana intoxication, no lay 
opinion can be admissible as common knowledge or understanding 
on that subject.  A lay witness may testify concerning a 
defendant's observable appearance, behavior, and demeanor, but 
may not offer an opinion as to the defendant's sobriety or 
intoxication.22  See State v. Schories, 827 N.W.2d 659, 666 (Iowa 
                                                          
 
22 We caution the Commonwealth that "a prosecutor who 
elicits from a police officer his or her special training or 
21 
 
2013) (expert testimony preferred on cause of intoxication for 
substances other than alcohol); State v. Noback, 309 Mont. 342, 
346 (2002) ("we are not persuaded that lay people are 
sufficiently knowledgeable about common symptoms of drug 
consumption . . . to offer lay opinion testimony"); State v. 
Bealor, 187 N.J. 574, 587 (2006) (court declined "to place lay 
opinion testimony regarding marijuana intoxication on the same 
footing as lay opinion testimony as to alcohol intoxication").  
See also Commonwealth v. Sliech-Brodeur, 457 Mass. 300, 
330 & n.43 (2010) (lay witness may not testify that individual 
suffers from mental illness, but may testify to observed 
behavior). 
 
With respect to the question of jurors' use of their own 
common sense, we recognize that jurors are the ultimate arbiters 
of the facts.  See Commonwealth v. Lykus, 367 Mass. 191, 197 
(1975).  As a general rule, trial judges routinely instruct 
jurors, and jurors are urged by counsel, "not [to] leave their 
common sense outside the jury room."  See Commonwealth v. 
Mutina, 366 Mass. 810, 820 (1975).  Jurors may use their common 
sense in evaluating whether the Commonwealth introduced 
                                                                                                                                                                                           
expertise in ascertaining whether a person is intoxicated risks 
transforming the police officer from a lay witness to an expert 
witness on this issue, and the admissibility of any opinion 
proffered on this issue may then be subject to the different 
standard applied to expert witnesses."  See Commonwealth v. 
Canty, 466 Mass. 535, 541 n.5 (2013). 
22 
 
sufficient evidence to satisfy its burden of proof.  See 
Commonwealth v. Cole, 380 Mass. 30, 35-36 (1980) (in context of 
criminal responsibility, jurors may rely on facts and 
circumstances surrounding crime to determine whether 
Commonwealth established defendant's sanity).  We rely on the 
judge's limiting instructions to inform jurors about the proper 
use of FST evidence.  See Commonwealth v. Jackson, 384 Mass. 
572, 579 (1981). 
 
Conclusion.  We answer the reported questions as follows: 
 
1.  "No."  Police officers may not testify to the 
administration and results of FSTs as they do in operating 
under the influence of alcohol prosecutions.  Police 
officers may testify to the administration of "roadside 
assessments" in the manner set forth in this opinion. 
 
 
2.  "No."  A lay witness may not offer an opinion that 
another person is "high" on marijuana. 
 
 
3.  "Yes."  A police officer may testify to observed 
physical characteristics of the driver such as blood shot 
eyes, drowsiness, and lack of coordination.  The officer is 
not permitted to offer an opinion that these 
characteristics mean that the driver is under the influence 
of marijuana. 
 
 
4.  "Yes."  Jurors are permitted to utilize their 
common sense in assessing trial evidence. 
 
 
The case is remanded to the District Court for further 
proceedings consistent with this opinion. 
 
 
 
 
 
 
 
So ordered. 
 
Appendix. 
 
 
Model Jury Instruction Regarding Roadside Assessments for Use in 
Prosecutions for Operating Under the Influence of Marijuana 
 
 
You heard testimony in this case that the defendant, at the 
request of a police officer, performed or attempted to perform 
various roadside assessments, such as [Here outline the nature 
of the evidence, e.g., walking a straight line, balancing on one 
foot].  These roadside assessments are not scientific tests of 
impairment by marijuana use.  A person may have difficulty 
performing these tasks for many reasons unrelated to the 
consumption of marijuana. 
 
 
It is for you to decide if the defendant's performance on 
these roadside assessments indicate that his [her] ability to 
operate a motor vehicle safely was impaired.  You may consider 
this evidence solely as it relates to the defendant's balance, 
coordination, mental clarity, ability to retain and follow 
directions, ability to perform tasks requiring divided 
attention, and other skills you may find are relevant to the 
safe operation of a motor vehicle. 
 
 
It is for you to determine how much, if any, weight to give 
the roadside assessments.  In making your determination, you may 
consider what the officer asked the defendant to do, the 
circumstances under which they were given and performed, and all 
of the other evidence in this case. 
 
 
Finally, evidence of how a defendant performed in roadside 
assessments, standing alone, is never enough to convict a 
defendant of operating under the influence of marijuana.