The impact of police arrest is extremely variable, depending upon the context of the abuse. Economic status has a tremendous effect. With recent changes in welfare policy, women can't escape violence anymore. It is easier for men to get away with abuse. In reasoning that men abuse because they can get away with it, economic dependency makes it easier for men to do so.
Race has an impact as well.
Mandatory arrest is universally applied in the province, rather, it is left to the discretion of individual officer who responds to an assault call. Theoretically, mandatory arrest was put in place as a result of studies from the early 1980's that showed a significant reduction in recurrence of violence when abusers were arrested and charged, even if they were not convicted. However, mandatory arrest is not consistently applied. There has been considerable criticism levelled against it, largely from Native women and women of colour, who believe it to be another form of discrimination against Native men and men of colour. If it is an immediate crisis, where it really seems that the man is going to kill the woman, then it does have a deterrent effect.