State v. Lopez, 173 A.3d 485

Background

On March 3, 2013, Trooper Colin Richter stopped Juan C. Lopez for erratic speeding on I-95, observed signs of intoxication (slurred speech, glassy/bloodshot eyes, odor of alcohol), and administered three standardized field sobriety tests, which Lopez failed.
Lopez refused a breath test; no chemical blood/urine/breath BAC evidence was introduced at trial.
The state pursued a behavioral DUI prosecution under Conn. Gen. Stat. § 14-227a(a)(1), relying on officer observations and expert testimony about field sobriety tests.
The state’s expert, forensic toxicologist Robert H. Powers, testified on the scientific basis of the tests and opined (based on hypotheticals matching Richter’s description) that such performance would correspond to a BAC of 0.12 or higher and impaired driving ability.
On cross-examination, the trial court sustained objections to two defense questions asking whether Powers knew if Lopez himself was intoxicated; the court allowed extensive other cross-examination probing Powers’ expertise and the hypothetical-BAC opinion.
The jury convicted Lopez of operating under the influence and driving with a suspended license; Harper, J., dissented in part and concurred in part, arguing the exclusion of the two questions was proper and harmless and would affirm the conviction.

Issues

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether the trial court improperly restricted cross-examination of the state’s toxicology expert by barring questions about the defendant’s intoxication	State: Exclusion proper because questions sought an expert’s opinion on the ultimate issue for the jury to decide	Lopez: Questions were aimed to clarify/expose that Powers’ hypothetical-BAC testimony did not speak to Lopez’s actual BAC; exclusion impaired confrontation rights	Held: Exclusion of the two questions was proper; they asked for an opinion on the ultimate issue and were outside the scope of cross-examination (Harper, J. would affirm)
Whether barring those questions was harmful error requiring reversal	State: Any restriction was harmless because ample cross-exam and other evidence supported conviction	Lopez: Exclusion allowed expert hypothetical-BAC testimony to improperly influence jury	Held: Harper, J. concluded any error was harmless given Richter’s testimony, jury instructions, lack of BAC evidence, and overall strength of behavioral evidence
Admissibility of altered/incomplete dash-cam video evidence	State: Video admissible	Lopez: Video should have been excluded as incomplete/altered	Held: Harper, J. concurred with majority that trial court did not abuse discretion in admitting the video
Proper scope of expert testimony on hypotheticals and ultimate issues	State: Expert may opine on hypotheticals; cannot opine on ultimate issue of intoxication	Lopez: Expert’s hypothetical BAC opinion effectively testified about defendant	Held: Experts may answer hypothetical questions; they cannot render opinions on the ultimate factual issue for the jury — trial court properly limited ultimate-issue testimony

Key Cases Cited

State v. Daniel B., 164 Conn. App. 318 (appellate decision on confrontation and scope of cross-examination of expert)
State v. Wright, 273 Conn. 418 (trial court discretion on admissibility and defendant’s obligations to follow rules of evidence)
State v. Taylor G., 315 Conn. 734 (expert witness may not opine on ultimate issue of fact)
State v. Rodriguez, 311 Conn. 80 (harmless error framework for nonconstitutional evidentiary rulings)
State v. A. M., 324 Conn. 190 (presumption that jury follows instructions)
State v. Purcell, 174 Conn. App. 401 (defendant must produce evidence jury disregarded instructions to rebut presumption)