If an individual thought they had been mistreated in some way at the border, or if their privacy rights had been violated, or if a border officer conducted themselves in a manner that the traveller found to be intrusive or offensive, they would have now, or as soon as the legislation is passed, the ability to file an independent complaint with the new agency. The agency would investigate and offer their conclusions as to whether the procedure at the border had been appropriate or not.
On June 17th, 2019. See this statement in context.