WASHINGTON (AP) _ The Supreme Court, reinvigorating language it used in a ruling 202 years ago, today threw out some of a Texas man's convictions for sexually assaulting his stepdaughter.

The justices, by a 5-4 vote, ruled that four of Scott Carmell's 15 convictions wrongly were based on a Texas law enacted after he allegedly committed the crimes.

At issue was one aspect of the Constitution's ban on laws that criminalize acts, or alter the evidence needed for a conviction, after the crime occurs.

``Under the law in effect at the time the acts were committed, the prosecution's case was legally insufficient ... unless the state could produce both the victim's testimony and corroborative evidence,'' Justice John Paul Stevens wrote for the court. ``Under the new law, (Carmell) could be (and was) convicted on the victim's testimony alone...''

``A law reducing the quantum of evidence required to convict an offender is as grossly unfair as, say, retrospectively eliminating an element of the offense,'' Stevens added.

Carmell was convicted in a Denton County court in 1997 on 15 counts of indecency with a child, sexual assault and aggravated sexual assault. Prosecutors said he engaged in various sex acts, including intercourse, with his stepdaughter over a four-year period, beginning in 1991 when she was 12 and a sixth-grader.

He was sentenced to life in prison on two convictions of aggravated sexual assault that were not at issue in today's case. He was sentenced to 20 years in prison on the other charges.

Under Texas law before 1993, no one could be convicted of a sexual offense based solely on an alleged victim's testimony unless they told a third party within six months of the alleged incident. However, an exception was made for alleged victims under 14.

The law was changed in 1993 to extend the exception to any alleged victim under 18.

The four alleged offenses at issue in this case took place between June, 1992 and July, 1993, when the victim was aged 14 or 15 and before the new law took effect.

Carmell contended that he should not have been convicted for incidents that allegedly occurred more than six months before his stepdaughter told his wife in 1995 about his conduct.

But he was prosecuted under the 1993 law.

Carmell's Supreme Court appeal relied heavily on language in a 1798 high court decision. It said the Constitution does more than bar laws that criminalize conduct after it occurs, or make a crime more serious than when it was committed.

The 1798 decision said the Constitution also bans ``every law that alters the legal rules of evidence, and receives less, or different, testimony than the law required at the time of the commission of the offense, in order to convict the offender.''

Despite that language, Texas courts and prosecutors and the Clinton administration said using the 1993 law did not violate Carmell's rights. Today, the Supreme Court disagreed.

Stevens' opinion was joined by Justices Antonin Scalia, David H. Souter, Clarence Thomas and Stephen G. Breyer.

Dissenting were Chief Justice William H. Rehnquist and Justices Ruth Bader Ginsburg, Sandra Day O'Connor and Anthony M. Kennedy.

Writing for the four, Ginsburg contended that ``retroactive changes to rules concerning the admissibility of evidence and the competency of witnesses to testify'' do not violate the Constitution.

According to court records, Carmell once worked as a counselor of incest victims, and met the woman he married in 1988 while counseling her. It was her daughter he sexually assaulted.

The case is Carmell vs. Texas, 98-7540.