Eighteen-year-old Sammy Yatim died last month after being shot multiple times and hit with a stun gun during a confrontation with police on an empty streetcar.
Conservative Steve Clark says the government should have acted sooner.
Police groups have been pushing for years to expand the use of the weapons, which have been restricted to supervisors and specialist officers.
The Liberals say their decision had nothing to do with Yatim's death and was years in the making.
They're now leaving it up to local police services to decide whether they want to equip all their officers with stun guns.
Police forces will also have to foot the bill, which will put pressure on already tight municipal budgets. Tasers cost about $1,500 each, including three cartridges.
Quebec is now the only province that won't allow frontline officers to carry stun guns.