My question is whether Wortman could have been arrested for possession of a mock police car and uniform before he started his shooting spree? The answer appears to be no.

Mere possession of these items is not a crime in Nova Scotia, so even if the police knew about the items they could not have done anything.

After he was driving around shooting people, there were plenty of reasons to arrest him. Impersonating an officer is just one more on a long list of potential charges.