It likely hasn't.... I know here in Edmonton, due to our cat by-laws, it is within your legal right to trap free-roaming cats. You can't kill them, you can't injure them, but you can trap them. And I could almost guarantee that those animals end up covered in their own feces and urine before they are turned over to the by-law officers. Unless we have a by-law regarding what you can legally trap them in, she likely didn't commit an offense simply by trapping the cat.
Oh, never mind, a quick check shows the people writing by-laws have more brains than I gave them credit for... lol.
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Cat Trapping
Animal Control Services does not capture stray and at-large cats, but does lend humane traps to residents between April 1 and October 31 (weather dependant). Animal Control Officers will pick up cats trapped in a City trap. All other cats can be brought to the Animal Services Facility during regular business hours.
City traps can be borrowed for three days at a time from the Animal Services Facility on a first come, first served basis. There is a refundable $75 deposit for each trap, payable by VISA, Mastercard, Debit card or cash. Cheques are not accepted.
It is illegal to put an animal in distress, so you will need to check the trap frequently and will have to provide food, water and shelter for the trapped cat until it is turned over to the City. The cat must also not be injured by the method you use to trap and transport it.