Humiliation and abuse were doled out almost daily at an Ontario institution for the developmentally disabled, punishment for infractions as minor as speaking out of turn, former residents allege in a class-action lawsuit against the provincial government.

"If we got caught talking, we had to get up with our pants down and walk around the play room with our pants down," recalled Marie Slark, 59, who spent nine years of her childhood at the Huronia Regional Centre.

In other instances, children whose behaviour earned them a "black mark" were kicked and struck by their peers at staff's insistence, she and another plaintiff, Patricia Seth, said in an interview.

Slark, Seth and thousands of other former residents are alleging systemic neglect and abuse at the Orillia, Ont., facility, which the province operated for 133 years. Some say they were forced to work in the fields for no money.

The $2-billion suit is set to begin Monday, three years after receiving the green light from an Ontario Superior Court judge.

It covers those institutionalized at the centre between 1945 and 2009, many of whom are now aged or dying.

Money aside, Slark said she wants the province to apologize "for what they put us through."

"They took our childhood from us," she said.

The Ontario government denies the allegations, which have not been proven in court.

In its submissions to the court, the province acknowledges there were incidents of abuse, but insists these were isolated and did not stem from neglect.

"Any serious abuse was not acceptable and was dealt with when it was identified," the document reads.

The province also maintains residents were cared for in a manner "consistent with the knowledge, experience and standards of the day" and benefited from living there.

The institution opened its doors in 1876 under the name Orillia Asylum for Idiots and closed in March 2009 — the oldest facility for people with a developmental disability at the time.

It has faced allegations of abuse and neglect in the past, including an 1960s article describing overcrowding so severe that people were sleeping head to head.

The 1970s saw several government-sponsored reports condemn the facility.

Some Huronia advocates have argued the centre had changed drastically in later years, becoming a vibrant community where residents had dances and parties.

For Slark and Seth, however, the experience was akin to imprisonment, they said.

"It was like living in a prison. The only thing is, we didn't know when we would even get out. We thought we were going to die here," said Seth, 55.

"We weren't even treated like human beings," Slark added.

Both were admitted to the institution in the 1960s at the age of six and seven, as wards of the state. At 16, Seth was placed in a group home on the premises, where she remained until she was discharged at the age of 21.

"Talk about living in fear. It was horrible," she said.

Years later, she still suffers nightmares and struggles to deal with people in a position of authority, she said.

Several former residents and their relatives as well as former staff members are expected to testify at the trial, which is scheduled to take place over three months.

The court will have to determine, among other things, whether there was systemic negligence, whether conditions at Huronia fell below the standard of care at the time and whether the province breached its fiduciary duty to protect the residents.