Here in Canada if you resist arrest and later it’s proven the arrest was unlawful then it’s actually self defence and the charges are dropped.

The problem is that the lawfulness of an arrest is extremely broad so it’s extremely unlikely that you can resist an arrest and be found not guilty.

A lot of people don’t understand that there is detained, which then becomes arrested which then becomes charged which then becomes held pending bail etc.

At any point up to and including being charged you can be let go. When you are arrested it doesn’t automatically mean charges. When you are charged the officer may issue a summons or you may go to the station to be processed and released.

Too many people equate being arrested with being charged and held. In a protest the cops may arrest people and then just release them without charges a few hours later like they might do with a drunk walking down the street causing a disturbance.