A California man suing the Boy Scouts of America over sexual abuse suffered at the hands of a volunteer Scout leader was so scarred by the incident that he once threw up outside a Taco Bell when he saw someone who looked like the man, he testified in the opening day of a civil trial.

The 20-year-old man, who was 13 when he was molested in 2007, told jurors Monday that shortly after the abuse he secretly taped the Scout leader making a partial confession because it was "a 13-year-old's word against a Scout leader, an adult."

Then, he dropped out of baseball — which had been his passion for seven years — stopped hanging out with friends and eventually enrolled in a home school program after the Scout leader began showing up in a parked car outside his high school.

"I felt scared. I felt like he was coming after me. I remember just hiding until his car went by (and) I felt kind of sick, he said. "One of the times I threw up just seeing his car."

The Scout volunteer, Al Stein, pleaded no contest to felony child endangerment in 2009 and is now a registered sex offender. He did not attend the trial Monday.

The victim, who is seeking punitive damages, was the first to take the stand in what is expected to be a monthlong civil trial that will center on whether the Boy Scouts were negligent in educating, warning and training parents, Scouts and volunteers about the dangers of sexual abuse.

The plaintiff's attorney, Tim Hale, won the right to draw from more than 30 years of "perversion" files as evidence as he tries to make the case that the Scouts knew the dangers of abuse within scouting were real and didn't do enough to prevent it.

The files that were allowed in by Santa Barbara County Superior Court Judge Donna Geck earlier this month include 16 years of documents — from 1991 to 2007 — that have not been made public previously. Hale told jurors they would receive a CD of 100,000 pages to review during deliberations and, in some cases, would be the first people in the United States to see the files outside the Scouts and attorneys on the case.

The Scouts maintain that the boy's abuse could not have been prevented in the first instance and that their youth protection program worked because he recognized the abuse, resisted and told his mother, thus preventing further abuse and more victims.

Hale told the jury in his opening remarks that when they deliberate they will receive a CD of 100,000 pages of files to review and will be the first people in the U.S. outside Scout leadership and attorneys to see the documents.

Hale said the Scouts recorded between 9,000 and 10,000 such files between 1920 and 2007. An attorney for the Scouts put the number at 7,500; the discrepancy wasn't explained.

"The Boy Scouts of America has a long and sordid history of child sexual abuse committed against young Scouts committed by Scout leaders and that timeline goes back, the files show, until at least the 1920s," he said.

"What has not been going on is notice to the public and notice to (the plaintiff) and his parents," the lawyer added.

The victim's name is being used in court, but The Associated Press does not generally name victims of sexual abuse.

An attorney for the Boy Scouts said in his opening statement that the "perversion" files were created to keep children safe by maintaining a master list of people ineligible to volunteer with the Scouts.

The organization acknowledges mistakes in the way sex abuse allegations were handled in the past but now has a robust child protection program, attorney Nicholas Heldt said.

From 2003 to 2007, a key period for the lawsuit, only 27 adult volunteers were kicked out annually for sexually abusing Scouts, although there were at least 1.5 million volunteers nationally, he said.

When the plaintiff was abused, the youth protection training worked because the boy recognized the abuse, resisted and told his mother, Heldt said. She, in turn, told local Scout leaders who informed law enforcement.

"This case is about training and whether training would have made a difference," he told jurors.

"I think this is a case in which the one instance of sexual abuse against (the plaintiff) could not have been prevented, and it wasn't prevented," he said. "But the training program may have helped prevent the second or the third instance of sexual abuse."

The current lawsuit alleges that Stein, now 37, pulled down the plaintiff's pants when he was 13 and fondled him while the two worked in the Christmas tree lot.

Stein pleaded no contest to felony child endangerment in 2009 and was sentenced to probation. He served time in prison after authorities discovered photos of naked children on his cellphone.