A former Vancouver high school teacher charged with 16 counts of gross indecency and indecent assault with former students said Wednesday he's sorry and didn't mean to hurt anyone.

Tom Ellison, 62, is on trial in provincial court in Vancouver for having sex with 12 female students while he was teaching the Quest outdoor program at Prince of Wales Secondary in the 1970s and 1980s.

Testifying in his own defence Wednesday, he said that he never thought that what was happening at the time was wrong.

Now, he says he can't believe he was "that stupid," saying he wouldn't have done it if he thought he would hurt someone.

"I apologize to you guys because you're my good friends," he told his former students in the courtroom.

"I just crossed the line, I know it was wrong," he added.

He described the Quest program as one that tried to break down the formal barriers between teachers and students, and said most of his contacts with students were not sexual.

Janet Rygnestad, one of the alleged victims, said the experiences still left impact over two decades later.

"Girls in our program, we were made to feel like we were lesser than the boys," she said. "He was playing on things he knew made you feel weak and small."

First relationship began in 1975

Ellison said he tried to boost the spirits of many students with compliments and friendship and knew he was taking a risk when some of the relationships became sexual.

His first such relationship with a female student began in 1975 and lasted two years. The ex-teacher said they were close friends, and that he finally gave in to his attraction even though he knew it was wrong.

The woman is not one of the 12 complainants in the case.

He also claims that it was extremely common in the 1970s for teachers, both male and female, to have affairs with their students.

It wasn't until 1988 that the Criminal Code explicitly prohibited persons in a position of trust from having sex under any circumstance with those under the age of 18, and 10 of the 12 women have said the encounters were consensual.

With files from the Canadian Press