MONTREAL—The trial of former Rosemere High school teacher Tania Pontbriand entered a new phase on Friday as her defence team began a counter-attack against her young accuser.

Pontbriand is accused of having a sexually explicit relationship with one of her students that lasted for two years. The boy has testified that he was 15 years old when the relationship began in 2002.

During the often-delayed trial, the then-teenager said that he and Pontbriand took elaborate steps to hide their relationship from many people including his mother and Pontbriand's husband.

The young man testified that when the relationship took place he did not realize how damaging it was. Now, Pontbriand's lawyers brought forward witnesses to defend the high school teacher.

On the stand Friday a former colleague, Keith Bellamy, described Pontbriand as being a dedicated teacher at Rosemere High who was very responsible and dedicated to her students. He praised Pontbriand for her involvement in extra-curricular activities, so much so that she began to cry inside the courtroom.

Bellamy said that many teachers had concerns about the young man, saying that the accuser was emotionally disturbed at the time. According to Bellamy, Pontbriand’s colleagues believed he used the teacher as a scapegoat as he suffered from many issues at home and school.

The witness also said he believed the boy was anorexic and that his marks dropped significantly during the alleged affair.

A second teacher, Suzanne Charbonneau, said Pontbriand was known to shower all her students with personal attention and signs of affection. She said Pontbriand routinely treated all her students to small gifts and restaurant meals, because of her big heart.

Charbonneau testified the alleged victim was not singled out for special attention, she added that she never noticed any unacceptable behaviour between Pontbriand and the teen, who is now in his mid-20s.

The prosecution found her testimony a bit too convenient and challenged Charbonneau during a round of tough cross examination.

Prosecutor Caroline Lafleur forced Bellamy to admit that he never saw Pontbriand outside of school and had nothing to add to a number of key facts already admitted into evidence. As for Charbonneau, the prosecution tried to challenge her credibility by suggesting her testimony was tainted by her ongoing friendship with Pontbriand.

Pontbriand has denied that any physical activity ever took place between her and the alleged victim. In May, a sleeping bag was produced by the prosecution that contained both Pontbriand and the accuser’s sexual fluids.

After Friday's testimony the trial is faced with yet another delay, and will resume on Dec. 10, 2012.