The Utah Court of Appeals must consider claims by a man who says prosecutors can't charge him with both incest and aggravated sexual assault for the same act, the Utah Supreme Court has ruled.

The 4-1 ruling, issued Friday, says the Court of Appeals misapplied rules and statutes governing conditional plea bargains.The result is that attorneys for Eugene Montoya will be allowed to argue their claim that double-dealing prosecutors wrongly charged their client with crimes that are mutually exclusive.

Montoya was charged by the Salt Lake County attorney's office in April 1991 with counts of incest and aggravated sexual assault. He challenged the complaint, pointing out that incest is limited to "circumstances not amounting to rape, rape of a child or aggravated sexual assault" - a limitation prosecutors had omitted from the charging document.

His lawyers said prosecutors could charge one or the other, but not both.

In 1992, prosecutors refiled the complaint, again including both crimes but this time charging them "in the alternative," meaning that the judge or jury would decide which Montoya was guilty of, depending on the facts of the case.

But again they excluded the limiting language in the incest statute, and again, defense attorneys said they were alleging both "rape and not-rape."

In the meantime, Montoya pleaded no contest to the incest charge, on condition he could appeal the issue as to whether the state had legally charged him.

The trial court accepted the conditional plea, but the Utah Court of Appeals rejected it. The judges said such pleas are only proper in cases where the disposition of the case hinges on the issue being appealed, and that wasn't the case with Montoya.

Chief Justice Michael Zimmerman, writing for the majority, said the Court of Appeals misinterpreted the law and procedures dealing with conditional pleas. The high court ordered the case remanded to the Court of Appeals, which will now decide whether prosecutors had been up-front in the first place.

"That's the real issue here," said Ronald S. Fujino, an appeals attorney with the Salt Lake Legal Defenders Association. "We don't think the prosecution was being honest in the first place."