The

on Thursday threw out sex abuse convictions against a former Portland girls track coach, the latest of dozens of child abuse convictions overturned in recent years because of

.

The high court ruled that medical experts can't testify at trial about their diagnoses of child sex abuse if no physical evidence exists. The finding has had significant ramifications, reversing at least 36 other child abuse convictions in the state so far.

Prosecutors have had to retry the cases, often calling the young witnesses back to the stand to testify years after the alleged abuse.

"The last thing anyone wants to do is put child abuse victims through another trial and make them come back years later to relive a very difficult part of their lives," said Anna M. Joyce, solicitor general with the Oregon Department of Justice's Appellate Division, who had argued the Supreme Court case.

threw out the conviction of Askia Brown, who was sentenced in 2009 to 20 months in prison and five years of probation after a jury found him guilty of molesting two teenage girls he privately trained in August 2008.

Other cases

In November 2011,

the Oregon Court of Appeals overturned a Tualatin man's conviction based on the same case law. The charges stemmed from an 8-year-old girl's allegation that Vladyslav Volynets-Vasylchenko had sexually abused her at a Beaverton in-home day care over three years. A new trial is set for this November.

In 2011

, an Astoria man successfully appealed his sex abuse convictions based on the same case law. A jury in 2008 had convicted Thomas Michael Kelly, 61, of 12 counts of first-degree sodomy and 12 counts of first-degree sexual abuse, based in part on the testimony of Dr. Roy Little, who was present when the 9-year-old girl reported the alleged abuse. At the trial, Little testified that the girl suffered from symptoms of sexual abuse, though there was no physical evidence to support the claim. Kelly was retried this year and convicted of 24 counts of sexual abuse and sodomy. He was sentenced to 33 1/4 years in prison.

Brown had been a girls track coach for Central Catholic High School in Southeast Portland, but the abuse occurred at his private studio, according to trial testimony.

Two girls, ages 14 and 15 at the time, said during the trial in Multnomah County Circuit Court that Brown had inappropriately touched them while giving them sports massages. The girls said Brown used massage lotion to rub them under their shorts and touch intimate parts of their body.

The state appeals court ruled that Multnomah County Judge John Wittmayer erred in admitting diagnoses from child abuse experts that one of the girls was sexually abused and that the second girl's case was "highly concerning for sexual abuse."

The diagnoses were from CARES Northwest, a child abuse assessment center that conducted a forensic exam of the two teenagers.

In his appeal, Brown's attorney, Oregon deputy public defender Kristin A. Carveth, cited the state Supreme Court's ruling in State v. Southard, which threw out the Deschutes County conviction of Kermit Eugene Southard. Southard had been convicted of sodomizing his girlfriend's 5-year-old son and 3-year-old daughter.

The Supreme Court said it considers three criteria to determine if medical diagnoses are admissible at trial: They must be relevant, possess sufficient scientific validity to be helpful to the jury and their prejudicial effect must not outweigh their evidentiary value. In Southard, the Supreme Court found the prejudicial effect was too much.

A diagnosis like the one in the Southard case uses videotaped interviews of the alleged victims and considers their history, reported behaviors and credibility to make a medical finding of child sex abuse.

"Because the doctor's diagnosis in this case did not tell the jury anything that it was not equally capable of determining, the marginal value of the diagnosis was slight. The risk of prejudice, however, was great," the state Supreme Court ruled.

The court held that a medical diagnosis of sex abuse isn't admissible when no physical evidence exists because a jury is more apt to defer to an expert's conclusion that an accuser is credible instead of making its own determination.

The Supreme Court's ruling came Oct. 1, 2009. Brown's trial occurred just beforehand, in August and September 2009, but the court's decision applied retroactively.

In the Brown case, lawyers from Oregon's Department of Justice conceded that the trial court made a mistake in admitting the diagnosis for both girls. But they countered that in one of the girl's cases, the diagnosis likely didn't unduly influence the jury because other physical evidence was presented at trial. The DNA collected from one girl matched Brown's male chromosome, according to trial testimony.

The Oregon Court of Appeals disagreed.

"Even though there was other evidence of sexual abuse, we cannot say that there is little likelihood that the diagnosis affected the verdict," it ruled. "Given the nature of the errors and the record as a whole, we cannot say that it was harmless error."

Brown, now 38, already has served his sentence, but the appeals decision wipes out his convictions and sex offender status. Multnomah County prosecutors said they'll examine whether to retry Brown.

"We're reviewing our options," said Multnomah County Chief Deputy District Attorney Don Rees.

Askia Brown

Neither Brown nor his attorneys could be reached for comment.

State prosecutors have bemoaned the Southard ruling. Medical diagnoses of sex abuse have helped bolster their prosecutions in difficult child abuse cases when there's no physical evidence, and it's the word of a child against an adult.

"It's been devastating," said Josh Marquis, Clatsop County district attorney and a former president of the Oregon District Attorney's Association. He estimated that at least three to four child abuse convictions have been sent back to trial court in his county.

"These cases are horrible to handle the first-time around," Marquis said. "It's been devastating, particularly when you have to make phone calls to victims where you've already told the family that everything was over with."

-- Maxine Bernstein