New workplace safety rules came into effect in Ontario Tuesday, the result of years of lobbying by the families of two southwestern Ontario women murdered by co-workers.

The changes to the Occupational Health and Safety Act come under Bill 168, which calls on employers to address domestic violence when it spills over into the workplace.

All employers across the province, whether they have two people working for them or 2,000, must have a plan to deal with workplace harassment.

Bill 168 is the first law in the country to cover domestic violence in the workplace.

Victory bittersweet for victims' families

Tuesday's change comes at the end of a long fight by the families of Lori Dupont and Theresa Vince.

Dupont, 36, was killed by her ex-boyfriend, Dr. Marc Daniel, in 2005 at Hotel-Dieu Grace Hospital in Windsor, Ont., where they both worked.

The hospital was aware Daniel had been harassing Dupont and that the situation was getting worse, but it did not discipline him.

'I'm so sorry that it took so long to come to fruition, and I'm so sorry that it didn't happen before Lori lost her life.' —Catherine Kedziora

After stabbing Dupont to death, Daniel took his own life.

Theresa Vince was shot in the face and killed in Chatham in 1996 by a boss who had sexually harassed her for more than a year and against whom she had filed a harassment complaint. Her family joined the Duponts at a news conference Tuesday in Windsor, Ont.

Both families said the bill isn't perfect but is better than what existed before.

"I'm so elated," said Vince's daughter, Catherine Kedziora. "I'm pleased. I'm very happy about Bill 168

"I'm so sorry that it took so long to come to fruition, and I'm so sorry that it didn't happen before Lori lost her life."

The families said they hope to never again read about a death from gender-based violence in the workplace.

"Seven or eight years ago, I told a reporter this was going to happen again when we couldn't get no place with legislation," said Theresa Vince's husband, Jim.

"I said it would happen again, and it's a sad, sad day when I pick up the paper and read about Lori Dupont. "

Employers must make sure a workplace violence policy is posted for employees and that workers are trained in the details of that policy.

They must also do a risk assessment to determine whether problems exist at their company.