PORTLAND, Ore. — The Boy Scouts of America has long kept an extensive archive of secret documents that chronicle the sexual abuse of young boys by Scout leaders over the years.

The “perversion files,” a nickname the Boy Scouts are said to have used for the documents, have rarely been seen by the public, but that could all change in an Oregon courtroom.

The attorney for a man who was molested in the 1980s by a Scout leader has obtained about 1,000 Boy Scouts sex files and is expected to release some of them at a trial that began Wednesday. The lawyer says the files show how the Boy Scouts have covered up abuse for decades.

The trial is significant because the files could offer a rare window into how the Boy Scouts have responded to sex abuse by Scout leaders. The only other time the documents are believed to have been presented at a trial was in the 1980s in Virginia.

At the start of the Oregon trial, lawyer Kelly Clark recited the Boy Scout oath and the promise to obey Scout law to be “trustworthy.” Then he presented six boxes of documents that he said will show “how the Boy Scouts of America broke that oath.”

Clark held up file folders he said contained reports of abuse from around the country, telling the jury the efforts to keep them secret may have actually set back efforts to prevent child abuse nationally. “The Boy Scouts of America ignored clear warning signs that Boy Scouts were being abused,” he said.

Charles Smith, attorney for the national Boy Scouts, said in his own opening statement the files were kept under wraps because they “were replete with confidential information.”

Smith told the jury the files helped national scouting leaders weed out sex offenders, especially repeat offenders who may have changed names or moved in order to join another local scouting organization.

Clark is seeking $14 million in damages on behalf of a 37-year-old man who was sexually molested in the early 1980s in Portland, Ore., by an assistant Scoutmaster, Timur Dykes.

Clark said the victim suffered mental health problems, bad grades, drug use, anxiety, difficulty maintaining relationships and lost several jobs over the years because of the abuse.

Dykes was convicted three times between 1983 and 1994 of sexually abusing boys, most of them Scouts.

Although there have been dozens of lawsuits against the organization over sex abuse allegations, judges for the most part have either denied requests for the files or the lawsuits have been settled before they went to trial.

The Boy Scouts had fought to keep the files being used in the Portland trial confidential. But they lost a pretrial legal battle when the Oregon Supreme Court rejected their argument that opening the files could damage the lives and reputations of people not a party to the lawsuit.

The lawsuit also named the Church of Jesus Christ of Latter-day Saints because the Mormons acted as a charter organization, or sponsor, for the local Boy Scouts troop that included the victim. But the church has settled its portion of the case.

The case centers on whether the Boy Scouts of America did enough to protect boys from Dykes. On Friday, testimony from a bishop for the Church of Jesus Christ of Latter-day Saints responsible for a Scout troop suggested the Scouts never provided training about spotting abuse or preventing it.

The bishop, Gordon McEwen, confronted Dykes after receiving a report of abuse by the mother of one boy in the troop in January 1983.

In a video deposition played Friday for the jury, the bishop said Dykes admitted abusing 17 boys and provided a written list of names. A retired police officer who investigated the abuse report testified that Dykes admitted having molested two boys and was arrested.

Clark told the jury Dykes continued with his scouting activities until he was arrested again in July 1984 during a routine traffic stop while he was driving a van full of Scouts on a camping trip.