Canadian criminal law

my husband is being falsely accused of sexually assaulting his 4.5 year old daughter, who lives on a native reserve with her mother and grandparents. this idea stemming from the fact that he bathed her, which they have not taught her to wash herself, so we have to wash her.

no charges have been laid. he has not talked to police or given a statement.

before this accusal, the mother/grandmother have denied him access and communication with his daughter for a month.

what do we do? can we sue? how would we go about that?

You cannot really sue for that if all they did was report it. The police should dismiss that if that is all that happened. But get counsel involved if it appears it may be investigated further or deeper.