You do since the courts assume the parties behave honorably (I.e. they assume there is no parallel construction)

Sadly this is an incredibly cogent concept. We saw this with Lavabit and when courts accept patently false LE testimony.

The system works when corruption and deceit aren't present or tolerated - when they are the institutions become suspect.

I don’t have much problems with assuming parties are honorable. In fact I don’t know how a justice system would work otherwise.

My problem is that our prosecutors are often dishonorable!

There is corruption and deceit in every system, which is why we must demand total transparency, checks and balances on all of our institutions.