I think the more important distinction to make is between compelled testimony and voluntary testimony.

I think we should encourage people to come forward of their own free will, both by making it safer to do so and by educating them on the benefits to society. In a sense I think this because I have faith in my local police, and see them as a part of the community, not as an "other."

Same as you, though, I don't believe believe in expanding their powers to compel people to come forward, because that obviously has scary negative consequences.

Will you still have faith in your local police and see them as a part of your community after the conduct a triple anal probe on you or your children and hand you with the invoice for the procedure?

While I generally support unions, the police fraternity mindset is troubling. There are no good cops as long as the blue code of silence is the de facto mode of operation.