SANTA FE — Calvin Finch had six convictions for drunken driving and no valid license.

But he wanted to buy a vehicle, and he had a prospect. An acquaintance at a holiday barbecue wanted to sell his truck, and he offered to let Finch test-drive it.

While turning from U.S. Highway 550 onto a San Juan County road, Finch waited for an oncoming car. He said he never saw the motorcycle behind it.

The cyclist, Harry Irvin, 62, died at the crash site on July 4, 2009. The rear of the truck collided with his oncoming motorcycle.

Garrett Morris, a San Juan County Sheriff's Office deputy, administered a field sobriety test to Finch. He passed. Deputies did not arrest him, though a couple would later say they thought Finch had been drinking.

He said he had some peppermint schnapps about 3 a.m., but that was 12 hours before the crash, and he was sober when the deadly accident occurred.

Deputies agreed to let Finch's girlfriend drive him to a hospital, where he had blood drawn. A blood-alcohol sample would better determine whether Finch had been drinking just before the crash.

Finch says his girlfriend drove first to her house, about a quarter-mile away, so she could change clothes and get her driver's license.

He said he was shaken to his core, horrified that the accident he had just been part of had killed a man.

As he waited for his girlfriend, he said, he began drinking more peppermint schnapps. By his account, he downed "several" drinks before they went to the hospital.

There, Finch's blood-alcohol reading was .13, well above the drunken-driving threshold of .08. This was about 2 1/2 hours after the crash.

Sheriff's deputies admitted that he had been left unattended for 20 minutes or so, and Finch said that was when he drank the alcohol.

A jury convicted him of vehicular homicide, his seventh drunken-driving offense, traffic violations and driving while his license was suspended or revoked.

District Judge William Birdsall sentenced Finch to 25 years in prison. His punishment was enhanced because the vehicular homicide conviction occurred after four drunken-driving convictions in the previous 10 years.

Finch appealed and won on the vehicular homicide conviction.

The state Court of Appeals, in a 3-0 decision last year, ruled that Birdsall committed a fundamental error in instructing the jury on vehicular homicide.

The appeals court said a conviction for that crime required proof that Finch was driving the truck while under the influence of intoxicating liquor, and that his drunkenness was a significant cause of Irvin's death.

Finch's defense was that he was not drunk when he was driving, only afterward.

The appeals court found that Birdsall failed to give the jury an appropriate instruction on cause. It said this was a fundamental error, so it reversed the vehicular homicide conviction and ordered that Finch receive a new trial.

Now the New Mexico Supreme Court will review that ruling. It will read briefs in Finch's case during September. No oral arguments in the case will be considered, according to the Supreme Court's schedule.

State Attorney General Gary King's staff says Finch's conviction should be reinstated. It wrote in its brief that the Court of Appeals "overstepped its authority by disregarding a Supreme Court precedent" on jury instructions.

The Supreme Court has held that a trial judge's failure to instruct a jury on causation is not a fundamental error, prosecutors said.

Finch's public defender pointed out that San Juan Sheriff's Office deputies said they lacked enough evidence to arrest Finch after the crash. This, the defense said, was a good indication that Finch was not drunk when the crash occurred.

His subsequent drinking of schnapps to escape his sorrow about the crash accounted for his high blood-alcohol level, the defense said.

State records show that Finch, now 53, is in the state prison in Lea County.

He had a significant record prior to the crash that killed Irvin, having served prison time for larceny, burglary and assault on a peace officer.

Milan Simonich, Santa Fe Bureau chief of Texas-New Mexico Newspapers, can be reached at 505-820-6898. His blog is at nmcapitolreport.com.