Case Title: Coffey v. Shiomoto

Citation: 

Docket Number: S213545

State: california

Court: California Supreme Court

Date: 2015-04-06T00:00:00Z

Document:
Filed 4/6/15 
 
 
 
IN THE SUPREME COURT OF CALIFORNIA 
 
 
 
ASHLEY JOURDAN COFFEY, 
) 
 
 
) 
 
Plaintiff and Appellant, 
) 
 
 
) 
S213545 
 
v. 
) 
 
 
) 
Ct.App. 4/3 G047562 
JEAN SHIOMOTO, as Director, etc., 
) 
 
) 
Orange County 
 
Defendant and Respondent. 
)  Super. Ct. No. 30-2012-00549559 
 
____________________________________) 
 
A California Highway Patrol officer stopped a car driven by plaintiff 
Ashley Jourdan Coffey after he observed her driving erratically.  Four subsequent 
chemical tests revealed her blood-alcohol concentration (BAC) ranged from 0.08 
to 0.096 percent.  The officer then confiscated plaintiff‘s driver‘s license and 
served her with a notice that her license would be suspended pursuant to Vehicle 
Code section 13382.1  In an administrative hearing to review the suspension, 
plaintiff‘s expert witness opined that her BAC was rising at the time of the 
chemical tests, suggesting her BAC was below the 0.08 percent threshold at the 
time plaintiff was driving.  Both the Department of Motor Vehicles (DMV) 
hearing officer and the trial court discounted the expert‘s testimony in part by 
relying on arrest reports, which described the physical manifestations of plaintiff‘s 
                                              
1  
All statutory references are to the Vehicle Code unless otherwise stated. 
 
2 
intoxication, such as her general appearance, erratic driving, poor performance on 
field sobriety tests, and the strong odor of alcohol she projected.  
We decide in this case whether the trial court erred by considering, in 
addition to the results of breath and blood tests, other circumstantial evidence of 
intoxication to conclude by a preponderance of the evidence that plaintiff drove 
with a BAC at or above 0.08 percent.  As we explain, we conclude the trial court 
did not err. 
FACTS 
On November 13, 2011, at 1:32 in the morning, Sergeant Martin of the 
California Highway Patrol was traveling southbound on State Route 55 in Orange 
County when he saw a car traveling 60 miles per hour, swerving erratically from 
side to side.  From the number four, or right-hand, lane, the car swerved one foot 
to the left into the number three lane before correcting.  It then twice swerved one 
to two feet to the right, onto the highway‘s shoulder.  Sergeant Martin positioned 
his patrol vehicle behind the car and activated his emergency lights, whereupon 
the car slowly moved left across the highway into the number one lane.  When 
Martin activated his siren, the car veered even further left, into the carpool lane.  
Only when Sergeant Martin used his public address system and directed the driver 
to pull to the right did the car eventually comply.   
Upon making contact with the driver of the vehicle, plaintiff Ashley 
Coffey, Sergeant Martin noticed her eyes were red and a strong odor of alcohol 
emanated from her car.  Officer White arrived to provide backup and confirmed 
these observations.  To both officers she denied having consumed any alcoholic 
beverages, offering the rather implausible story that she had just turned 21 years 
old, had been in a bar, but had not herself consumed any alcoholic beverages.  The 
officers then had plaintiff perform various field sobriety tests.  Plaintiff failed the 
horizontal gaze nystagmus test, ―display[ing] a lack of smooth pursuit in both 
 
3 
eyes.‖2  Asked to complete the ―walk-and-turn test,‖ in which she was asked to 
walk heel to toe for nine steps, turn counterclockwise, and then walk back heel to 
toe, ―she missed heel to toe on five of those nine steps by 2–4 inches on each step.  
When she reached step nine, . . . she turned clockwise instead of counter clockwise 
as instructed. . . .  [She] used both feet to make the turn instead of keeping her 
front foot in place‖ and on the return similarly ―missed heel to toe three of the 
steps by 2–4 inches.‖3   
                                              
2  
― ‗Nystagmus is an involuntary rapid movement of the eyeball, which may 
be horizontal, vertical, or rotary.  [Citation.]  An inability of the eyes to maintain 
visual fixation as they are turned from side to side (in other words, jerking or 
bouncing) is known as horizontal gaze nystagmus, or HGN.  [Citation.]  Some 
investigators believe alcohol intoxication increases the frequency and amplitude of 
HGN and causes HGN to occur at a smaller angle of deviation from the forward 
direction.‘ ‖  (People v. Leahy (1994) 8 Cal.4th 587, 592.) 
 
3  
The ― ‗walk-and-turn test‘ ‖ is significant because it tests ― ‗many of the 
same skills needed for driving,‘ such as small muscle control, information 
processing, reaction, balance, coordination, and short-term memory.‖  (U.S. v. 
Stanton (9th Cir. 2007) 501 F.3d 1093, 1100.)   
 
―Officers administering the Walk-and-Turn test observe the suspect‘s 
performance for eight clues: 
 
―• can‘t balance during instructions; 
 
―• starts too soon; 
 
―• stops while walking; 
 
―• doesn‘t touch heel-to-toe; 
 
―• steps off line; 
 
―• uses arms to balance; 
 
―• loses balance on turn or turns incorrectly; and, 
 
―• takes the wrong number of steps.‖   
(Utah Prosecution Council, Driving Under the Influence Prosecution Manual 
(2007) ch. 8, p. 8  [as of April 6, 2015] (Utah Prosecution 
Manual).)  ―Original research shows that if a suspect exhibits two or more of the 
clues, or cannot complete the test, the suspect‘s BAC is likely to be above 0.10 
[percent].  This criterion has been shown to be accurate 68 percent of the time.‖  
(Ibid.)  
 
4 
Plaintiff did somewhat better on the ―one-leg stand‖ test,4 standing on one 
foot and counting out loud beginning with 1,001; the test was terminated when she 
reached 1,022 after 30 seconds.  On the Romberg test,5 ―[s]he swayed slightly in 
                                              
4  
In the ―one-leg stand‖ test, after listening to the instructions, ―the subject 
must raise one leg, either leg, with the foot approximately six inches off the 
ground, keeping raised foot parallel to the ground.  While looking at the elevated 
foot, count out loud in the following manner: 
 
― ‗[O]ne thousand and one‘, ‗one thousand and two‘, ‗one thousand and 
three‘ until told to stop.  This divides the subject‘s attention between balancing 
(standing on one foot) and small muscle control (counting out loud). 
 
―The timing for a thirty-second period by the officer is an important part of 
the One-Leg Stand test.  The original research has shown that many impaired 
subjects are able to stand on one leg for up to 25 seconds, but that few can do so 
for 30 seconds. 
 
―One-Leg Stand is also administered and interpreted in a standardized 
manner.  Officers carefully observe the suspect‘s performance and look for 
four specific clues: 
 
―• sways while balancing; 
 
―• uses arms to balance; 
 
―• hops; 
 
―• puts foot down. 
 
―Inability to complete the One-Leg Stand test occurs when the suspect: 
 
―• puts the foot down three or more times, during the 30-second period; 
 
―• cannot do the test. 
 
―The original research shows that, when the suspect produces two or more 
clues or is unable to complete the test, it is likely that the BAC is above 0.10 
[percent].  This criterion has been shown to be accurate 65 percent of the time.‖ 
(Utah Prosecution Manual, supra, ch. 8, at pp. 8–9  [as of April 6, 2015].) 
 
5  
In the Romberg test, the driver is ―asked to stand at attention, close his 
eyes, tilt his head back, and estimate the passage of 30 seconds.‖  (People v. 
Bejasa (2012) 205 Cal.App.4th 26, 33.)  The officer observes the driver‘s ―balance 
and his ability to accurately measure the passage of 30 seconds.‖  (Ibid.)  
 
 
5 
all directions from center by 1–2 inches‖ and ―estimated 30 seconds at 37 actual 
seconds.‖  Plaintiff refused to perform a preliminary alcohol screening, or PAS.6   
Based on the officers‘ observations of plaintiff and her poor performance 
on the field sobriety tests, they placed her under arrest at 2:00 a.m.  Officer White 
advised her of the implied consent law7 and she chose to perform a breath test, 
although she failed several times to provide an adequate breath sample and had to 
be retested multiple times.  At 2:28 a.m., 56 minutes after she was stopped by 
Sergeant Martin, her breath test registered a BAC of 0.08 percent.  Three minutes 
later, at 2:31 a.m., her second breath test measured a BAC of 0.09 percent.  Police 
then transported plaintiff to the Orange County jail, where she elected to have her 
blood drawn.  The blood draw occurred at 2:55 a.m., one hour 23 minutes after 
plaintiff was pulled over by Sergeant Martin.  The first test of the blood sample 
showed a BAC of 0.095 percent; the second measured 0.096 percent.  As a result 
of these chemical test results, Officer White confiscated plaintiff‘s driver‘s license 
                                              
6  
Pursuant to section 23612, subdivision (h), a PAS is an investigative tool 
used to determine whether there is reasonable cause for arrest.  ―[A] preliminary 
test is ‗distinguished from the chemical testing of a driver‘s blood, breath or urine 
contemplated by the implied consent law [citation] which is administered after the 
driver is arrested, [and is] sometimes referred to as ―evidentiary‖ [or evidential] 
testing.‘ ‖  (People v. Vangelder (2013) 58 Cal.4th 1, 5, fn. 1.) 
 
7  
―A person who drives a motor vehicle is deemed to have given his or her 
consent to chemical testing of his or her blood or breath for the purpose of 
determining the alcoholic content of his or her blood, if lawfully arrested for an 
offense allegedly committed in violation of Section 23140, 23152, or 23153.‖  
(§ 23612, subd. (a)(1)(A).)  ―The person shall be told that his or her failure to 
submit to, or the failure to complete, the required chemical testing will result in a 
fine, mandatory imprisonment if the person is convicted of a violation of Section 
23152 or 23153, and . . . suspension or revocation of the person‘s privilege to 
operate a motor vehicle . . . .‖  (§ 23612, subd. (a)(1)(D).)  
 
 
6 
and issued her an ―administrative per se suspension/revocation order‖ and 
temporary driver‘s license.  (§ 13382; see Lake v. Reed (1997) 16 Cal.4th 448, 
454–455 (Lake).)  
Plaintiff, charged with drunk driving (§ 23152), was allowed to plead to a 
―wet reckless‖ (§§ 23103 [misdemeanor reckless driving], 23103.5 [prosecutorial 
statement that alcohol was involved]; see People v. Claire (1991) 229 Cal.App.3d 
647, 650 & fn. 2), but requested a hearing before the DMV to challenge her 
license suspension (§ 13558).   
At the ensuing administrative hearing, the DMV hearing officer had before 
her the ―Officer‘s Sworn Statement‖ form, Officer White‘s arrest report and the 
supplemental reports of Sergeant Martin and Officer White.  In addition to 
considering these documents, the hearing officer heard telephonic testimony from 
Jay Williams, a forensic toxicologist with extensive experience, who testified for 
plaintiff.  Williams noted the result of plaintiff‘s first breath test was 0.08 percent, 
the second test three minutes later was 0.09 percent, and her blood sample taken 
about 20 minutes later tested at 0.095 and 0.096 percent.  According to Williams, 
these results suggested the alcohol level in plaintiff‘s body was rising at the time 
of the tests and, given the totality of the circumstances, were consistent with 
plaintiff‘s BAC being below 0.08 percent at 1:32 a.m. when she was first pulled 
over by Sergeant Martin. 
The DMV hearing officer rejected Williams‘s testimony regarding a rising 
BAC, explaining in her ruling that the witness‘s two conclusions—first, that 
plaintiff‘s BAC was rising at the time she was pulled over, and second, that it may 
accordingly be deduced that her BAC was below 0.08 percent when she was 
driving—were not supported by reliable evidence, were ―too speculative to 
support the contention,‖ and were ―based on a subjective interpretation of the 
evidence.‖  In addition, Williams‘s conclusions were ―insufficient to rebut the 
 
7 
official duty presumption,‖ which in this context we take to be a reference to the 
presumption the chemical test results were valid.8  The hearing officer reached this 
conclusion, she explained, because Williams had not himself examined the breath-
analyzing device used in the case, offered no opinion whether it was in working 
order, conducted no scientific tests himself, and ―did not show that any other 
experts in the scientific community had reached similar conclusions.‖  Finally, the 
hearing officer specifically found credible Officer White‘s recordation of the 
―events as they occur[red],‖ which we assume meant White‘s observations of 
plaintiff‘s appearance and her performance on field sobriety tests.  Accordingly, 
the hearing officer concluded plaintiff‘s license suspension was proper because the 
state had shown by a preponderance of the evidence that she had been driving with 
a BAC of 0.08 percent or higher.  
Plaintiff filed a petition for a writ of mandate with the trial court to 
challenge the DMV hearing officer‘s decision.  After first noting that section 
23152, subdivision (b) makes it a rebuttable presumption that a person was driving 
with a BAC of 0.08 percent or higher if so tested at that level or higher within 
three hours of driving (see discussion, post), the trial court denied the writ, 
                                              
8  
Evidence Code section 664 provides in part:  ―It is presumed that official 
duty has been regularly performed.‖  Applied in this context, ―Evidence Code 
section 664 creates a rebuttable presumption that blood-alcohol test results 
recorded on official forms were obtained by following the regulations and 
guidelines of [Cal. Code Regs.] title 17.  [Citations.]  Test results from authorized 
laboratories, performed by public employees within the scope of their duties, are 
admissible under the public employee records exception to the hearsay rule.  
[Citations.]  The recorded test results are presumptively valid and the DMV is not 
required to present additional foundational evidence.  [Citation.]  At this point, 
‗faced with a report of chemical test results, the burden would be on the licensee to 
demonstrate that the test was not properly performed.‘ ‖  (Shannon v. Gourley 
(2002) 103 Cal.App.4th 60, 64–65.) 
 
 
8 
explaining that ―[e]ven assuming that petitioner Coffey rebutted [this] 
presumption . . . , there was sufficient evidence based on the blood-alcohol tests 
and the other circumstantial evidence based on the assessment, observations and 
tests by the arresting officers at the scene to support the DMV hearing officer‘s 
decision under the weight of the evidence.‖  (Italics added.)   
The Court of Appeal affirmed.  In determining whether the trial court‘s 
decision was supported by substantial evidence, the appellate court opined that 
―[t]he issue boils down to whether non-chemical-test circumstantial evidence can 
prove that Coffey‘s BAC at the time of driving was consistent with her BAC at the 
time of her chemical tests.‖  Relying on this court‘s opinion in Burg v. Municipal 
Court (1983) 35 Cal.3d 257, the appellate court held in the affirmative.  We 
granted review. 
DISCUSSION 
A.  Background 
The DMV suspended plaintiff‘s license to drive pursuant to the 
―administrative per se‖ law, ―under which a person arrested for driving under the 
influence of alcohol, and who is determined to have a prohibited amount of 
alcohol in his or her blood, must have driving privileges suspended prior to an 
actual conviction for a criminal offense.‖  (Lake, supra, 16 Cal.4th at p. 454.)  As 
we explained in that case, ― ‗[t]he express legislative purposes of the 
administrative suspension procedure are:  (1) to provide safety to persons using the 
highways by quickly suspending the driving privilege of persons who drive with 
excessive blood-alcohol levels; (2) to guard against erroneous deprivation by 
providing a prompt administrative review of the suspension; and (3) to place no 
restriction on the ability of a prosecutor to pursue related criminal actions.‘ ‖  
(Ibid.)  ―[T]he administrative per se laws were deemed necessary due to the time 
 
9 
lag that often occurs between an arrest and a conviction for driving while 
intoxicated or with a prohibited BAC.  During this interim period, arrestees who 
could eventually be convicted of an intoxication-related driving offense were 
permitted to continue driving and, possibly, endangering the public thereby.  
Moreover, without administrative per se laws, persons with extremely high BAC 
levels at the time of arrest could escape license suspension or revocation by plea 
bargaining to lesser crimes or entering pretrial diversion.  Thus, by providing for 
an administrative license suspension prior to the criminal proceeding, the law 
affords the public added protection.‖  (Id. at pp. 454–455.) 
Pursuant to the administrative per se law, ―[a]fter either the arresting officer 
or the DMV serves a person with a ‗notice of an order of suspension or revocation 
of the person‘s [driver‘s license],‘ the DMV automatically reviews the merits of 
the suspension or revocation.  [Citation.]  The standard of review is preponderance 
of the evidence [citation], and the department bears the burden of proof.‖  (Lake, 
supra, 16 Cal.4th at p. 455.)  A driver served with such a suspension notice is 
entitled to a hearing on request (§ 13558, subd. (a)), at which the only issues to be 
decided for drivers such as plaintiff9 are whether the arresting officer had 
reasonable cause to believe she was driving, whether she was arrested for an 
enumerated offense, and whether she was driving with 0.08 percent BAC or 
higher.  (§ 13557, subd. (b)(3)(A), (B), & (C)(i).)  If the DMV hearing officer 
finds these three statutory prerequisites proved by a preponderance of the 
evidence, the accused‘s driver‘s license will be suspended for four months if the 
                                              
9  
Somewhat different rules apply to those under 21 years of age (§ 13557, 
subd. (b)(3)(C)(ii)), those driving commercial vehicles (id., subd. (b)(3)(C)(iv)), 
and those on probation for prior drunk driving convictions (id., subd. 
(b)(3)(C)(v)). 
 
 
10 
driver has had a clean driving record (§ 13353.3, subd. (b)(1)).  Higher penalties 
apply to those with prior drunk driving convictions.  (§ 13353.3, subd. (b)(2).)   
B.  The Rebuttable Presumption in Section 23152 
We first address whether the presumption created by section 23152, 
subdivision (b) controls this case.  That provision states in part:  ―In any 
prosecution under this subdivision, it is a rebuttable presumption that the person 
had 0.08 percent or more, by weight, of alcohol in his or her blood at the time of 
driving the vehicle if the person had 0.08 percent or more, by weight, of alcohol in 
his or her blood at the time of the performance of a chemical test within three 
hours after the driving.‖  Although the statutory language speaks in terms of a 
―prosecution,‖ several Courts of Appeal have held this presumption is not limited 
to criminal prosecutions but also applies in administrative license suspension 
proceedings.  (Corrigan v. Zolin (1996) 47 Cal.App.4th 230, 236, citing Jackson v. 
Department of Motor Vehicles (1994) 22 Cal.App.4th 730, 740, fn. 9, and Bell v. 
Department of Motor Vehicles (1992) 11 Cal.App.4th 304, 310–313.)    
Extending the reach of Vehicle Code section 23152, subdivision (b)‘s 
evidentiary presumption to administrative per se proceedings would be consistent 
with the legislative history of that provision.  The need for the presumption ―arose 
from the absence in ‗[e]xisting law‘ of any ‗provision for the delay involved 
between the time a person is arrested for [driving under the influence] and when 
the chemical test for BAC is actually administered,‘ of any ‗means to determine a 
person‘s BAC at the time the person is actually driving the car,‘ or of any 
‗mention of time parameters for the administering of chemical tests and for their 
admission as [admissible] evidence into a court of law.‘  (Health & Welf. Agency, 
Dept. of Alcohol & Drug Programs, Enrolled Bill Rep. for Sen. Bill No. 745 
(1981–1982 Reg. Sess.) Sept. 1982, original italics.)  Thus, in enacting the 
 
11 
presumption, the Legislature intended (1) to ‗diminish the arguments that ha[d] 
arisen when extrapolating the [BAC] at the time of the test back to the time of the 
driving‘ (Bus. & Transportation Agency, DMV, Enrolled Bill Rep. for Sen. Bill 
No. 745 (1981–1982 Reg. Sess.) Sept. 1982), (2) ‗to close a potential loophole in 
the current law, whereby a person . . . could claim that he or she had consumed . . . 
alcohol which had not yet been absorbed into the bloodstream while the person 
was operating the vehicle, but which later raised the blood alcohol level‘ 
(Governor‘s Office, Dept. of Legal Affairs, Enrolled Bill Rep. for Sen. Bill No. 
745 (1981–1982 Reg. Sess.) Sept. 1982), and (3) ‗to recognize that alcohol 
concentrations dissipate over time, so that a person whose blood alcohol levels 
exceed the permissible concentrations at the time of the test, was likely to have 
had unlawfully high blood alcohol levels when driving . . . .‘ ‖  (Bell v. 
Department of Motor Vehicles, supra, 11 Cal.App.4th at p. 311.)  These three 
statements of legislative intent would arguably apply to administrative per se 
proceedings as well. 
Consistent with the previously cited Court of Appeal cases, both parties 
assume section 23152‘s presumption applies in administrative per se hearings.  We 
need not resolve that question, however, because even were the presumption 
applicable, it was rebutted in this case.  An explanation of how the presumption 
operates can be found in the Evidence Code.  Section 601 of that code provides:  
―A presumption is either conclusive or rebuttable.  Every rebuttable presumption 
is either (a) a presumption affecting the burden of producing evidence or (b) a 
presumption affecting the burden of proof.‖  Vehicle Code section 23152, 
subdivision (b), by its terms, creates a rebuttable presumption, and we agree with 
the parties that it establishes a presumption affecting the burden of producing 
evidence, not the burden of proof.  A statute transferring the burden of proof to a 
driver facing a criminal charge of drunk driving would raise serious constitutional 
 
12 
questions (see Ulster County Court v. Allen (1979) 442 U.S. 140, 157 [a 
permissive presumption is constitutional if, among other things, it ―does not shift 
the burden of proof‖]; see People v. Gamache (2010) 48 Cal.4th 347, 376 
[rejecting claim that jury instruction ―impermissibly alters the burden of proof,‖ 
explaining the ―instruction does not establish an unconstitutional mandatory 
presumption in favor of guilt [citation] or otherwise shift or lower the 
prosecution‘s burden of establishing guilt beyond a reasonable doubt‖]), and 
although those concerns are inapplicable here because it is an administrative per se 
proceeding, neither party argues for a different construction.  (See People v. 
Dubon (2001) 90 Cal.App.4th 944, 953 [―When a presumption is established to 
facilitate the determination of the particular action in which the presumption is 
applied, rather than to implement public policy, it is a presumption affecting the 
burden of producing evidence.‖].) 
A rebuttable presumption requires the trier of fact, given a showing of the 
preliminary fact (here, that a chemical test result showed plaintiff had a BAC of 
0.08 percent or more within three hours of driving), to assume the existence of the 
presumed fact (here, that plaintiff had been driving with a prohibited BAC) 
―unless and until evidence is introduced which would support a finding of its 
nonexistence, in which case the trier of fact shall determine the existence or 
nonexistence of the presumed fact from the evidence and without regard to the 
presumption.‖  (Evid. Code, § 604.)  In other words, if evidence sufficient to 
negate the presumed fact is presented, the ―presumption disappears‖ (Craig v. 
Brown & Root, Inc. (2000) 84 Cal.App.4th 416, 421) and ―has no further effect‖ 
(In re Heather B. (1992) 9 Cal.App.4th 535, 561), although ―inferences may 
nevertheless be drawn from the same circumstances that gave rise to the 
presumption in the first place‖ (Craig v. Brown & Root, Inc., supra, at p. 421; see 
 
13 
Evid. Code, § 604 [―Nothing in this section shall be construed to prevent the 
drawing of any inference that may be appropriate‖]). 
Assuming the results of her breath and blood tests gave rise to a 
presumption she was driving with a BAC of 0.08 percent or more, plaintiff argues 
the testimony of her expert witness, Jay Williams, supplied the necessary contrary 
evidence sufficient to rebut the presumption.  By contrast, the DMV argues 
Williams‘s testimony was insufficient, arguing that evidence necessary to rebut 
the presumption must be substantial, i.e., ― ‗reasonable in nature, credible, and of 
solid value; it must actually be ―substantial‖ proof of the essentials which the law 
requires in a particular case.‘ ‖  Asserting the DMV hearing officer‘s refusal to 
credit Williams‘s views shows his testimony was insubstantial, the DMV argues 
his testimony was accordingly insufficient to rebut the statutory presumption. 
The DMV misapprehends Evidence Code section 604.  That section 
provides that evidence is sufficient to rebut a presumption if it ―would support a 
finding of [the] nonexistence of‖ the presumed fact.  (Italics added.)  The most 
reasonable meaning of this phrase is that if the predicate facts are found, Vehicle 
Code section 23152‘s presumption will apply unless the driver presents evidence 
which, if believed, ―would support a finding of [the] nonexistence of‖ the 
presumed fact.  This plain meaning of the statutory language is supported by the 
Assembly Committee on Judiciary‘s comment on section 604, which states:  
―Such a presumption is merely a preliminary assumption in the absence of 
contrary evidence, i.e., evidence sufficient to sustain a finding of the nonexistence 
of the presumed fact.  If contrary evidence is introduced, the trier of fact must 
weigh the inferences arising from the facts that gave rise to the presumption 
against the contrary evidence and resolve the conflict.  For example, if a party 
proves that a letter was mailed, the trier of fact is required to find that the letter 
was received in the absence of any believable contrary evidence.  However, if the 
 
14 
adverse party denies receipt, the presumption is gone from the case.  The trier of 
fact must then weigh the denial of receipt against the inference of receipt arising 
from proof of mailing and decide whether or not the letter was received.‖  (Assem. 
Com. on Judiciary com., reprinted at 29B pt. 2, West‘s Ann. Evid. Code (1995 ed.) 
foll. § 604, p. 59.) 
Viewing the presumption in section 23152, subdivision (b) in this way, and 
assuming without deciding that it applies in administrative per se proceedings,10 
we find Williams‘s testimony was sufficient to rebut the presumption that 
plaintiff‘s BAC was at least 0.08 percent at the time she was driving.  Williams 
was qualified as an expert in the field and his testimony was clear and direct.  If 
believed, his evidence would have justified a conclusion that plaintiff‘s BAC was 
rising at the time of her chemical tests and was thus quite possibly below the 0.08 
percent threshold at the time she had been driving.  As a consequence, the DMV 
was required to prove plaintiff‘s BAC at the time she was driving without resort to 
the statutory presumption. 
C.  The Circumstantial Evidence of Plaintiff’s Intoxication Was 
Relevant and Thus Admissible  
Having found the statutory presumption in section 23152, subdivision (b), 
even if applicable, does not control this case, we turn to the main issue presented 
here:  Did the DMV hearing officer properly admit and consider non-chemical-test 
                                              
10  
The Legislature might in the future wish to clarify whether it intends that 
the evidentiary presumption in section 23152 applies in administrative per se 
proceedings as well as in ―prosecutions.‖ 
 
 
15 
evidence to reach her conclusion that plaintiff was driving with at least a 0.08 
percent BAC?11 
The crime of drunk driving is set forth in section 23152 and can be 
established in two ways:  Subdivision (a) states that ―[i]t is unlawful for a person 
who is under the influence of any alcoholic beverage to drive a vehicle.‖  To prove 
a violation under subdivision (a), the People must present evidence the driver‘s 
alcohol consumption impaired his or her ability to drive.  (People v. McNeal 
(2009) 46 Cal.4th 1183, 1197.)  Subdivision (b) offers an alternative method of 
proof; it states that ―[i]t is unlawful for a person who has 0.08 percent or more, by 
weight, of alcohol in his or her blood to drive a vehicle.‖  To prove a criminal 
violation under subdivision (b), the People need not prove the accused‘s driving 
ability was impaired or diminished, but only that the driver‘s BAC reached or 
exceeded the prohibited level at the time the accused was driving. 
The administrative per se law‘s license suspension provision, although not a 
criminal matter, is linked to the second prong of section 23152.12  Thus, license 
                                              
11  
Plaintiff notes the DMV hearing officer failed to submit to cross-
examination so that it might be determined how she used the circumstantial 
evidence to reach her conclusion to reject the testimony of expert witness Jay 
Williams.  This failure, she argues, violated her right to due process of law.  
Although it seems extremely dubious that plaintiff‘s due process rights require the 
hearing officer to testify and submit to plaintiff‘s cross-examination, the record in 
any event reveals no objection on this ground or request that the officer testify.  
Accordingly, plaintiff forfeited this claim. 
 
12  
We are not here concerned with the less typical administrative per se 
provisions applicable to underage or commercial drivers, or those on probation for 
drunk driving (see §§ 13353.2, subd. (a)(2) [person under 21 years old with a BAC 
of 0.01 percent or greater], 13353.2, subd. (a)(3) [person driving a vehicle 
requiring a commercial driver‘s license with a BAC of 0.04 percent or greater], 
13353.2, subd. (a)(4) [person on probation for drunk driving with a BAC of 0.01 
percent or greater]), or to adults who refuse to submit to, or complete, a chemical 
 
(footnote continued on next page) 
 
16 
suspension under the administrative per se law does not require proof of a person‘s 
impairment to safely operate a motor vehicle due to alcohol consumption, but only 
that the person‘s BAC level was 0.08 percent or more.  Section 13382, subdivision 
(a) provides in pertinent part:  ―If the chemical test results for a person who has 
been arrested for a violation of Section 23152 or 23153 show that the person has 
0.08 percent or more, by weight, of alcohol in the person‘s blood, . . . the peace 
officer, acting on behalf of the [DMV], shall serve a notice of order of suspension 
or revocation of the person‘s privilege to operate a motor vehicle personally on the 
arrested person.‖  (Italics added.)  In this case, the DMV presented the results of 
four chemical tests showing plaintiff‘s BAC was at or above 0.08 percent.  Given 
the presentation of these facially qualifying chemical test results, did the hearing 
officer abuse her discretion in concluding that non-chemical-test evidence was 
relevant and thus admissible to bolster or corroborate the chemical test results? 
Plaintiff argues reliance on the non-chemical-test circumstantial evidence 
was improper because such evidence cannot by itself establish whether her BAC 
was 0.08 percent, higher than 0.08 percent, or lower than that level.  She cites to 
scientific evidence showing that physical manifestations of alcohol intoxication 
can occur at levels much lower than a BAC of 0.08 percent and that observable 
physical symptoms correlate poorly to actual BAC levels.  She also argues that 
one study has shown that poor performance on field sobriety tests has a low 
correlation to whether a driver‘s BAC is over 0.08 percent.  (Hlastala, Polissar & 
                                                                                                                                                              
 
(footnote continued from previous page) 
 
test as requested by a law enforcement officer (§ 13353) or to underage drivers 
(§ 13388) or adults on probation for drunk driving (§ 13389) who refuse to submit 
to a preliminary alcohol screening (§ 13353.1, subd. (a)). 
 
 
17 
Oberman, Statistical Evaluation of Standardized Filed Sobriety Tests (May 2005) 
50 J. Forensic Science, No. 3, p. 662.) 
Unmentioned is that some studies have reached a contrary conclusion.  For 
example, the National Highway Traffic Safety Administration (NHTSA) released 
the results of a study in 1998 that evaluated the accuracy of the standardized field 
sobriety test (SFST) battery at BACs below 0.10 percent.  (Stuster and Burns, 
Final Rep. to NHTSA, Validation of the Standardized Field Sobriety Test Battery 
at BACs Below 0.10 Percent (1998).)  The NHTSA‘s study found that the battery 
of SFSTs, which includes three of the tests administered to plaintiff (the horizontal 
gaze nystagmus test, the ―walk-and-turn test,‖ and the ―one-leg stand test‖), when 
administered by a trained officer, are ―extremely accurate in discriminating 
between BACs above and below 0.08 percent.‖  (Id., at p. v, italics added.)  The 
NHTSA‘s report expressly dispelled a common misapprehension ―that field 
sobriety tests are designed to measure driving impairment.‖  (Id., at p. 28.)  
According to the NHTSA, the SFST battery is instead designed specifically to 
―provide statistically valid and reliable indications of a driver‘s BAC, rather than 
indications of driving impairment.‖  
We are not here attempting to resolve the scientific debate over the use of 
SFSTs to predict BAC.  As plaintiff acknowledges, the test for admissibility of 
evidence is not a strict one:  As a general matter, evidence may be admitted if 
relevant (Evid. Code, § 350), and ― ‗[r]elevant evidence‘ means evidence . . . 
having any tendency in reason to prove or disprove any disputed fact that is of 
consequence to the determination of the action‖ (id., § 210).  ― ‗ ―The test of 
relevance is whether the evidence tends, ‗logically, naturally, and by reasonable 
inference‘ to establish material facts . . . .‖ ‘ ‖  (People v. Wilson (2006) 38 Cal.4th 
1237, 1245.)  ―The trial court has broad discretion to determine the relevance of 
evidence [citation], and we will not disturb the court‘s exercise of that discretion 
 
18 
unless it acted in an arbitrary, capricious or patently absurd manner.‖  (People v. 
Jones (2013) 57 Cal.4th 899, 947.) 
Past cases applying this standard have found circumstantial evidence of 
intoxication may be admissible when later-administered chemical tests show a 
BAC exceeding the legal limit.  In Burg v. Municipal Court, supra, 35 Cal.3d 257 
(Burg), decided at a time when the BAC threshold for drunk driving was 0.10 
percent,13 we explained that the crime of drunk driving set forth in section 23152, 
subdivision (b) ―prohibits driving a vehicle with a blood-alcohol level of 0.10 
percent or higher; it does not prohibit driving a vehicle when a subsequent test 
shows a level of 0.10 percent or more.  Circumstantial evidence will generally be 
necessary to establish the requisite blood-alcohol level called for by the statute.  A 
test for the proportion of alcohol in the blood will, obviously, be the usual type of 
circumstantial evidence, but of course the test is not conclusive:  the defendant 
remains free to challenge the accuracy of the test result, the manner in which it 
was administered, and by whom.  (People v. Lewis (1983) 148 Cal.App.3d 614, 
620; accord, Fuenning v. Superior Court (Ariz. 1983) 680 P.2d 121, 127. . . 
[rejecting argument that analogous statute represents ‗substitution of a machine 
test result for a jury verdict‘ because defendant is given an opportunity to 
challenge accuracy of test result, and state must prove beyond a reasonable doubt 
that defendant‘s blood-alcohol level was 0.10 percent at the time he was driving]; 
Cooley v. Municipality Anchorage (Alaska App. 1982) 649 P.2d 251, 254–255.)  
Of course, both parties may also adduce other circumstantial evidence tending to 
                                              
13  
See former section 23152, subdivision (b), as amended by Statutes 1982, 
chapter 1337, section 1, page 4961.  The administrative per se law was enacted 
several years later in 1998.  (See Stats. 1998, ch. 118, § 4, pp. 757–758.) 
 
 
19 
establish that the defendant did or did not have a 0.10 percent blood-alcohol level 
while driving.  (See, e.g., Fuenning, supra, at p. 130.)‖  (Burg, supra, at p. 266, 
fn. 10, italics added.)  
Plaintiff would distinguish Burg, supra, 35 Cal.3d 257, as a case involving 
a criminal drunk driving prosecution, not an administrative per se matter, but if 
non-chemical-test circumstantial evidence of intoxication may be admissible in a 
criminal case where the People‘s burden of proof is beyond a reasonable doubt, we 
see no reason why such evidence would be categorically inadmissible in an 
administrative proceeding where the People‘s burden of proof is only a 
preponderance of the evidence.  Decisions in the Courts of Appeal support this 
conclusion.  Thus, in McKinney v. Department of Motor Vehicles (1992) 5 
Cal.App.4th 519, the Court of Appeal considered whether sufficient evidence 
supported the suspension of a driver‘s license under the administrative per se law.  
Citing Burg, the McKinney court noted that administration of a chemical test 
(blood, breath or urine) ―is not the only means of establishing that a driver‘s 
[BAC] was .08 or more.  [¶] . . . [B]oth parties are free to introduce circumstantial 
evidence bearing on whether the driver‘s [BAC] exceeded the permissible level.  
[Citation.]  ‗Evidence regarding the manner in which a defendant drove, 
performed field sobriety tests, and behaved is admissible and relevant as tending 
to establish that he did or did not have a 0.10 [now 0.08] [BAC] while driving.‘ ‖  
(McKinney, at p. 526, fn. 6; see Jackson v. Department of Motor Vehicles, supra, 
22 Cal.App.4th at p. 741 [―circumstantial evidence other than chemical test results 
may properly be admitted to establish a driver had the proscribed level of blood-
alcohol at the time of the offense‖]; People v. Randolph (1989) 213 Cal.App.3d 
Supp. 1, 7 [same].)   
Plaintiff argues Burg, supra, 35 Cal.3d 257, is unpersuasive because, apart 
from the single sentence referencing non-chemical-test circumstantial evidence, 
 
20 
the opinion does not elaborate on the use of such evidence to prove a driver‘s 
BAC.  But Burg‘s citation to Fuenning v. Superior Court, supra, 139 Ariz. 590 
[680 P.2d 121] (Fuenning), following that sentence is significant.14  In that case, a 
person charged with drunk driving argued that circumstantial evidence ―regarding 
the manner in which he was driving, [and] the manner in which he performed the 
field sobriety tests,‖ while relevant to the issue of whether he drove under the 
influence of alcohol, was ―irrelevant to the question of whether he . . . [was] 
driving with a .10% or greater BAC.‖  (Fuenning, supra, at p. 599.)  The Supreme 
Court of Arizona rejected the argument, explaining the evidence was relevant and 
thus admissible:  ―We agree with defendant that the only ultimate issue is whether 
defendant had a BAC of .10% or greater.  In each case in which a violation of [the 
.10 percent BAC law] is charged, the state will present evidence of the test and the 
issue will be whether the test results were an accurate measurement of the 
defendant‘s BAC at the time of arrest.  Typically, defendants will attack the 
margin of error, the conversion rate, the calibration of the test instrument, the 
technique used by the operator, the absorption and detoxification factors, etc.  
Evidence of defendant’s conduct and behavior—good or bad—will be relevant to 
the jury’s determination of whether the test results are an accurate measurement 
of alcohol concentration at the time of the conduct charged.  For instance, the test 
in the case at bench was given several hours after the arrest and showed a .11% 
BAC.  Defendant attacked the results, presenting evidence regarding margin of 
                                              
14  
Fuenning was later superseded by statute on a different point of law.  (See 
State ex rel. McDougall v. Superior Court in and for County of Maricopa (1995) 
181 Ariz. 202, 205–206 [888 P.2d 1389, 1392–1393].)  This subsequent history 
does not affect Fuenning‘s discussion of the admissibility of circumstantial 
evidence of intoxication. 
 
 
21 
error, time lapse and other factors.  Such evidence might raise considerable doubt 
whether the test result of .11% indicated .10% or greater BAC at the time 
defendant was arrested.  Evidence that at that time the person charged smelled 
strongly of alcohol, was unable to stand without help, suffered from nausea, 
dizziness or any of the other ‘symptoms’ of intoxication would justify an inference 
that a test administered some time after arrest probably produced lower readings 
than that which would have been produced had the test been administered at the 
moment of arrest.  The converse is also true.  Evidence that at the time of arrest 
defendant was in perfect control, displayed none of the symptoms of intoxication 
and had not driven in an erratic manner, is relevant to show that a reading of .11% 
from a test given some time later does not prove beyond a reasonable doubt that 
the defendant was driving with a .10% or greater BAC at the time of his arrest.  
Such evidence has been held admissible.  [Citations.]  Again, evidence is 
admissible when it is relevant.‖  (Fuenning, supra, at p. 599, italics added.)   
Plaintiff argues Fuenning is neither controlling nor even on point because it 
did not address the issue before us in the instant case.  Although Fuenning is an 
Arizona case and thus admittedly not controlling here (see Farmers Ins. Group v. 
County of Santa Clara (1995) 11 Cal.4th 992, 1018), it persuasively explains why 
circumstantial evidence of intoxication, while not dispositive, may be relevant and 
thus admissible15 to help interpret the results of a chemical test for a driver‘s 
BAC.  Moreover, because the Legislature has prohibited driving with a BAC of 
0.08 percent or higher, that being the threshold at which a person cannot safely 
operate a motor vehicle due to alcohol consumption, circumstantial evidence that 
plaintiff was weaving erratically all over the roadway, smelled strongly of alcohol, 
                                              
15  
To the extent plaintiff argues Fuenning, supra, 139 Ariz. 590, did not 
address the admissibility issue, she is simply incorrect. 
 
22 
and failed a battery of field sobriety tests may bolster chemical test results 
showing that she had attained or exceeded that BAC level. 
The administrative per se scheme in section 13382 is triggered by a 
chemical test result showing a BAC of 0.08 percent or more, and we do not here 
confront a case in which the DMV failed to present such test results; indeed, the 
DMV produced the results of four such tests.  In other words, neither the DMV 
hearing officer nor the trial court considered circumstantial evidence of 
intoxication in the absence of any chemical test results.  Although we find non-
chemical-test evidence of plaintiff‘s intoxication may be relevant and thus 
admissible in the typical administrative per se proceeding triggered by a BAC of 
0.08 percent or more to help connect those test results to a driver‘s BAC at the 
time she was driving (subject, of course, to the hearing officer‘s routine exercise 
of discretion), we would in any event affirm the hearing officer‘s decision in this 
case because the non-chemical-test evidence was admissible to rebut plaintiff‘s 
proffered defense that her BAC was low at the time she was driving and only later 
rose to exceed the legal limit.  Her expert, Jay Williams, testified that, in his 
opinion, the four chemical test results indicated plaintiff‘s BAC was rising at the 
time of the tests; from that supposition, he further deduced that plaintiff‘s BAC 
was below the 0.08 percent threshold at the time she was driving.  Even assuming 
that non-chemical-test evidence cannot by itself prove a driver‘s exact BAC at the 
moment the driver is stopped by a police officer, in this case plaintiff‘s erratic 
driving, outward appearance of substantial intoxication, implausible story of 
having just turned 21 years old, and was coming from a bar without having 
imbibed alcohol at all, and her failure on multiple field sobriety tests, together tend 
to rebut Williams‘s theory of a rising BAC and corroborate the BAC test results.  
For example, plaintiff‘s extremely erratic driving, observed by Sergeant Martin 
from before the moment he first made contact with her, suggests she was quite 
 
23 
intoxicated from that early point in the timeline and tends to refute the expert‘s 
speculation that her BAC was low at the time she was driving, but rose to 0.08 
percent and above only after she was stopped.  Whether the circumstantial 
evidence of plaintiff‘s intoxication was admitted to bolster the results of the 
chemical tests or merely to rebut plaintiff‘s defense of a rising BAC, the hearing 
officer did not act in ―an arbitrary, capricious or patently absurd manner‖ and thus 
did not abuse her broad discretion.  (People v. Jones, supra, 57 Cal.4th at p. 947.) 
Brenner v. Department of Motor Vehicles (2010) 189 Cal.App.4th 365, 
cited by plaintiff, does not warrant a contrary result.  In that case, an expert 
examined the maintenance records for the device used to measure the driver‘s 
breath and opined that it produced slightly elevated results.  As the driver‘s test 
results showed a BAC of 0.08 percent exactly, the expert opined the driver‘s 
actual BAC was slightly below the legal limit.  Because the trial court in Brenner 
had granted the driver‘s petition for a writ, the Court of Appeal was required to 
uphold that decision if supported by substantial evidence.  By contrast, the instant 
case comes to us in the opposite procedural posture:  the trial court here denied 
relief to plaintiff and we are bound to uphold that decision if supported by 
substantial evidence.  To the extent the appellate court in Brenner asserted that 
―the impressions of the officer may have a bearing on plaintiff‘s level of 
impairment, [but] they have no bearing on the precise level of his BAC‖ (id. at 
p. 373), the statement must be read in the context of the case:  Because the 
chemical tests in Brenner were done on a miscalibrated device used to measure the 
BAC in a breath sample, no accurate chemical test results were presented.  No 
such problem exists in the instant case; the DMV presented the results of four 
chemical tests and, although plaintiff‘s expert would have interpreted those results 
to conclude her BAC was rising, he did not testify they inaccurately measured her 
BAC at the time the tests were run.  To the extent the court‘s statement in Brenner 
 
24 
v. Department of Motor Vehicles, supra, 189 Cal.App.4th 365, may be taken to 
preclude consideration of non-chemical-test evidence to bolster or corroborate 
chemical test results, we disapprove it. 
Having concluded the DMV hearing officer properly admitted the 
circumstantial, nontest evidence of plaintiff‘s intoxication, we also conclude 
substantial evidence supported the trial court‘s decision to deny writ relief, thereby 
sustaining the DMV hearing officer‘s decision to suspend plaintiff‘s license to 
drive.  A driver whose license has been suspended under the administrative per se 
law can seek review of the DMV‘s decision by seeking a writ of mandate in the 
trial court.  ―In ruling on an application for a writ of mandate following an order of 
suspension or revocation, a trial court is required to determine, based on its 
independent judgment, ‗ ―whether the weight of the evidence supported the 
administrative decision.‖ ‘ ‖  (Lake, supra, 16 Cal.4th at p. 456.)  Following the 
trial court‘s denial of the writ, the scope of our review on appeal is limited:  ―[W]e 
‗need only review the record to determine whether the trial court‘s findings are 
supported by substantial evidence.‘  [Citation.]  ‗ ―We must resolve all evidentiary 
conflicts and draw all legitimate and reasonable inferences in favor of the trial 
court‘s decision.  [Citations.]  Where the evidence supports more than one 
inference, we may not substitute our deductions for the trial court‘s.  [Citation.]  
We may overturn the trial court‘s factual findings only if the evidence before the 
trial court is insufficient as a matter of law to sustain those findings.‖ ‘ ‖  (Lake, 
supra, at p. 457.)   
Applying this standard, we have no trouble concluding substantial evidence 
supported the trial court‘s ruling, for it acted well within its discretion in rejecting 
the expert‘s testimony and placing primary emphasis on the four chemical tests 
that showed plaintiff‘s BAC met or exceeded the statutory threshold at the time 
plaintiff was driving.  Neither the DMV hearing officer nor the trial court was 
 
25 
required to accept Williams‘s testimony at face value.  (People v. Prince (1988) 
203 Cal.App.3d 848, 858 [trier of fact ―is permitted to consider the credibility of 
the expert witnesses, the reasons given for their opinions, and the facts and other 
matters upon which their opinions are based‖]; cf. CALCRIM No. 332 [instructing 
the jury it is not required to accept a proffered expert opinion as ―true or 
correct‖].)  Both reasonably relied on circumstantial evidence of plaintiff‘s 
intoxication—her general appearance, the odor of alcohol about her person, her 
erratic driving, and her failed field sobriety tests—to support the accuracy of the 
chemical test results and to reject Williams‘s view of the evidence, including his 
opinion of a rising BAC, as unduly speculative.   
 
26 
 
CONCLUSION 
The judgment of the Court of Appeal is affirmed. 
 
 
 
 
 
 
 
WERDEGAR, J. 
 
WE CONCUR: 
 
CANTIL-SAKAUYE, C. J. 
CHIN, J. 
CORRIGAN, J. 
CUÉLLAR, J. 
KRUGER, J. 
 
1 
 
 
 
 
 
 
 
 
CONCURRING OPINION BY LIU, J. 
 
 
I write separately to clarify the limited way in which evidence of behavioral 
impairment was relevant in this case to determining whether the driver‘s blood-
alcohol concentration (BAC) was 0.08 percent or higher at the time of arrest. 
― ‗Relevant evidence‘ means evidence . . . having any tendency in reason to 
prove or disprove any disputed fact that is of consequence to the determination of 
the action.‖  (Evid. Code, § 210.)  Evidence that a driver‘s behavior is not 
impaired tends to prove that her BAC was below 0.08 percent because we can 
rationally surmise, given the Legislature‘s choice of the 0.08 percent BAC 
threshold, that a BAC of 0.08 percent is associated with an unsafe degree of 
impairment.  But the converse is not true.  Absent foundational evidence, a 
driver‘s impairment does not generally tend to show that her BAC was 0.08 
percent or higher because we have no way of correlating a specific type or degree 
of impairment with a particular BAC in a close case.  The fact that 0.08 percent 
BAC is a threshold associated with an unsafe degree of impairment does not imply 
that no impairment occurs below that threshold.  Without evidence that correlates 
particular behavioral impairments with particular BAC levels, signs of impairment 
do not generally establish that it is more likely a driver‘s BAC is 0.08 percent as 
opposed to 0.06 or 0.07 percent.  In other words, signs of impairment do not 
generally have a tendency in reason to prove a BAC of 0.08 percent or greater. 
 
2 
I say ―generally‖ because sometimes evidence of impairment can be so 
extreme — for example, if the driver passed out at the scene of arrest — that the 
trier of fact may infer on the basis of common experience that the driver likely was 
driving with a BAC of 0.08 percent or higher.  But there is no evidence of such 
extreme impairment in this case. 
Today‘s opinion properly refrains from suggesting that there is a correlation 
between evidence of impairment, including field sobriety test results, and a BAC 
of 0.08 percent or greater.  The court cites a study commissioned by the National 
Highway Traffic Safety Administration (NHTSA) reporting that at least some field 
sobriety tests, properly administered, may accurately measure a BAC of 0.08 
percent or greater.  (Stuster and Burns, Final Rep. to NHTSA, Validation of the 
Standardized Field Sobriety Test Battery at BACs Below 0.10 Percent (1998) 
p. v.)  But today‘s opinion is careful to express no view about the merits of these 
claims (maj. opn., ante, at p. 17), and other courts have questioned them.  In 
United States v. Horn (D.Md. 2002) 185 F.Supp.2d 530, for example, the court 
undertook an extensive review of expert testimony and academic literature 
critiquing an earlier NHTSA study and concluded that ―presently there is 
insufficient data to support these claims of accuracy‖ of field sobriety tests in 
predicting BAC.  (Id. at p. 556.) 
This lack of correlation between evidence of impairment and BAC does not 
mean that such evidence is always irrelevant.  As the New Mexico Supreme Court 
has explained, ―behavioral evidence by itself cannot be sufficient to show the 
required nexus between a BAC test and an earlier BAC.  It may, however, have 
limited relevance when the factors that underlie the shape of the concentration 
time curve [showing the level of alcohol absorption over time] are subject to 
conflicting testimony.‖  (State v. Day (N.M. 2008) 176 P.3d 1091, 1100.) 
 
3 
That is precisely how such evidence is relevant in this case.  The results of 
the four tests of Ashley Coffey‘s BAC indicated that it was rising, and the parties 
offer competing explanations.  Coffey argues that her BAC was in fact rising and 
that her BAC must have been below 0.08 percent at the time of her arrest.  By 
contrast, the Attorney General attributes the rising BAC test results to the test‘s 
margin of error (which would explain the 0.01 percent rise within three minutes 
between the first and second breath tests) and to the fact that the last two tests 
were blood tests rather than breath tests and thus produced slightly different 
results.  The Attorney General asserts that the testimony of Coffey‘s expert, Jay 
Williams, lacked key findings to support a rising BAC theory, such as when 
Coffey had her last drink before getting behind the wheel, her food intake, her 
weight, and other factors.  As the Department of Motor Vehicles (DMV) hearing 
officer concluded, Williams did not show that other experts in the scientific 
community had reached similar conclusions based on facts similar to those in this 
record. 
Evidence of Coffey‘s impairment was relevant to deciding which theory of 
rising BAC was more likely correct.  Such evidence was relevant in the following 
limited sense:  The fact that Coffey did show signs of impairment made her theory 
of rising BAC weaker than if Coffey had not shown signs of impairment at the 
time of her arrest.  (See maj. opn., ante, at p. 22 [―[T]he non-chemical-test 
evidence was admissible to rebut plaintiff‘s proffered defense that her BAC was 
low at the time she was driving and only later rose to exceed the legal limit.‖].)  
This point, on which all members of the court agree, renders unnecessary any 
broader suggestion that in a typical administrative per se proceeding, evidence of a 
driver‘s impairment tends to prove a BAC level of 0.08 percent or higher at the 
time of arrest.  Here the evidence of Coffey‘s impairment was, like the other 
 
4 
weaknesses in the expert‘s testimony discussed above, relevant to the DMV 
hearing officer‘s conclusion that the rising BAC theory was ―too speculative.‖ 
Because the evidence of Coffey‘s impairment was relevant in the limited 
way just described, and because the evidence is sufficient to support the 
determinations of the DMV hearing officer and the trial court that Coffey drove 
with a BAC at or above 0.08 percent, I concur in the judgment. 
 
 
 
 
 
 
 
 
LIU, J. 
 
1 
 
See next page for addresses and telephone numbers for counsel who argued in Supreme Court. 
 
Name of Opinion Coffey v. Shiomoto 
__________________________________________________________________________________ 
 
Unpublished Opinion 
Original Appeal 
Original Proceeding 
Review Granted XXX 218 Cal.App.4th 1288 
Rehearing Granted 
 
__________________________________________________________________________________ 
 
Opinion No. S213545 
Date Filed: April 6, 2015 
__________________________________________________________________________________ 
 
Court: Superior 
County: Orange 
Judge: Robert J. Moss 
 
__________________________________________________________________________________ 
 
Counsel: 
 
Law Offices of Chad R. Maddox and Chad R. Maddox for Plaintiff and appellant. 
 
Kamala D. Harris, Attorney General, Alicia M.B. Fowler, Kenneth C. Jones and Kevin K. Hosn, Deputy 
Attorneys General, for Defendant and Respondent. 
 
 
 
 
 
 
 
2 
 
 
 
 
 
Counsel who argued in Supreme Court (not intended for publication with opinion): 
 
Chad R. Maddox 
Law Offices of Chad R. Maddox 
5120 E. La Palma, #207 
Anaheim Hills, CA  92807 
(714) 695-1500 
 
Kevin K. Hosn 
Deputy Attorney General 
300 South Spring Street, Suite 1702 
Los Angeles, CA  90013 
(213) 897-2091