From the Globe and Mail:

A gun collector who was arrested outside his east-end apartment during a midnight raid has launched a $6.5-million lawsuit against the Toronto police, his former landlords and a tipster.
Peter Sedge, 59, said he was removed from his Beaches home at gunpoint wearing only his underwear during the May, 2008, seizure of about 120 legally collected firearms.
“I was scared because as soon as I opened the door, they were all screaming at me,” he told The Globe and Mail. “I could see guns pointed at me. . . . I totally scrambled at this point.”
The raid came hours after police got a tip about a cache of firearms and ammunition from a man who had viewed the property with his father – a prospective buyer – and Mr. Sedge’s landlord, Court documents say.
In August, 2008, the property was sold to a company owned by the man’s family.
The raid, and charges that were later dropped, were part of a negligent investigation that caused him humiliation and mental anguish, Mr. Sedge alleges in his statement of claim. His construction business, PS Fabricating Ltd., also suffered, he says.
Mr. Sedge’s lawyer, Arkadi Bouchelev, called the arrest “completely unnecessary” because his client was licensed and had no criminal record. Ontario’s chief firearms officer, who is in charge of licensing, could have been called in to inspect the site or confirm Mr. Sedge’s licence and registration, Mr. Bouchelev said.

This story is a sad commentary on the fact that, despite the existence of a firearms licence database and mandatory registration, that information is often ignored in favour of a “no-knock” armed assault on the home of a law-abiding citizen.
Unfortunately, courts and legislatures have set the bar for suing the police or the Crown extremely high and such lawsuits rarely succeed. In any event this is one to watch with interest.