Robert John, Law Office of Robert John, and Lawrence F. Reger, McConahy, Zimmerman & Wallace, Fairbanks, for Petitioner.
Eric A. Ringsmuth, Assistant Attorney General, Office of Special Prosecutions and Appeals, Anchorage, and Talis J. Colberg, Attorney General, Juneau, for Respondent.
Before : FABE, Chief Justice, EASTAUGH, CARPENETI, WINFREE, and CHRISTEN, Justices.
FABE, Chief Justice.
In 2004 the Alaska Legislature made two significant changes to the driving under the influence (DUI) law. First, the legislature amended subsection (a)(2) of AS 28.35.030 to provide that a person commits a DUI offense if the person takes a chemical test within four hours of driving that detects a blood alcohol level of at least 0.08 percent, regardless of the person's blood alcohol at the time of driving. This is known as the " blood-alcohol-level" theory of DUI. Second, the legislature barred defendants charged with DUI from presenting a " delayed-absorption" defense claiming that the results of their post-arrest chemical tests did not accurately indicate their blood alcohol level at the time they were driving. These two amendments did not revise the language of subsection (a)(1) of AS 28.35.030, which makes it a crime to drive while under the influence of alcohol, regardless of blood alcohol, and is known as the " under-the-influence" DUI theory.
Douglas Valentine was convicted under the amended DUI law in a general verdict that did not specify whether he was convicted under the blood-alcohol-level theory, the under-the-influence theory, or both. The court of appeals affirmed his conviction upon concluding that the 2004 amendments survived all of Valentine's constitutional challenges. But Judge David Mannheimer dissented in part, concluding that defendants are denied due process of law when they are barred from offering delayed-absorption evidence in prosecutions that rely on chemical test results and are brought under the under-the-influence theory. He reasoned that because DUI convictions under this theory continue to require proof that the defendants were under the influence at the time of driving, " the evidentiary prohibition codified in AS 28.35.030(s) violates a defendant's right to due process of law." 
We granted Valentine's petition for hearing. We conclude that the legislature properly exercised its broad authority to redefine the blood-alcohol-level theory of the DUI offense. But we agree with Judge Mannheimer that defendants are denied due process if they are barred from presenting delayed-absorption evidence in prosecutions relying on chemical test results to prove that they are guilty of a DUI offense under subsection (a)(1)'s under-the-influence theory. Because the jury's general verdict did not specify which theory provided the basis for Valentine's conviction, we reverse the conviction and remand for a new trial.
II. FACTS AND PROCEEDINGS
On June 18, 2005, at about 8:45 p.m., Fairbanks Police Sergeant Dan Welborn stopped Douglas Valentine for speeding. He noticed that Valentine had a moderate odor of alcohol and that his eyes were watery and bloodshot. Sergeant Welborn administered three field sobriety tests, which Valentine failed, and then placed Valentine under arrest. At the station at 9:20 p.m., Valentine submitted to a breath test, which showed a blood alcohol level of 0.099 percent. Valentine requested an independent test, which he obtained at 9:45 p.m. That blood test showed a blood alcohol level of 0.119 percent. The State charged Valentine under both AS 28.35.030 theories for committing a DUI offense: it alleged that Valentine was under the influence at the time of driving under subsection (a)(1) and that a chemical test showed that Valentine's blood alcohol level was above the legal limit under subsection (a)(2).
Before trial, Valentine filed a motion to dismiss, challenging the constitutionality of the 2004 amendments to the DUI law. District Court Judge Winston S. Burbank denied the motion to dismiss. In his decision, Judge Burbank incorporated by reference an earlier ruling by District Court Judge Raymond Funk rejecting the same constitutional claims in a consolidated Fairbanks case, State v. Baxley, Marshall & Tyler.  The effect of the district court's ruling was to prohibit Valentine from offering evidence to show that even though his blood alcohol level was above the legal limit at the time of his two chemical tests, he was not guilty of driving while under the influence under either theory because at the time he drove the alcohol he had consumed had not yet been fully absorbed into his bloodstream.
Valentine's case then proceeded to trial Before Superior Court Judge Donald D. Hopwood, who was sitting pro tem for the district court. At trial, Valentine argued that he had consumed two beers, that people absorb alcohol at different rates, that there was ample evidence that he was not impaired at the time he performed the field sobriety tests, and that the State had no evidence of his actual blood alcohol level at the time of driving. The jury convicted Valentine using a general verdict form that did not specify whether he was convicted under subsection (a)(1), subsection (a)(2), or both.
Valentine appealed the denial of his motion to dismiss. The court of appeals affirmed Valentine's conviction, concluding that the amendments to the DUI law withstood all of Valentine's constitutional challenges. The court of appeals determined that (1) the amendments are not unconstitutionally vague; (2) the amendments are not unconstitutionally overbroad; (3) the amendments do not impose criminal liability without any proof of mens rea; (4) the amendments do not violate Valentine's right to due process by creating impermissible presumptions; (5) the amendments do not deny Valentine's right to an independent test; (6) the amendments ...