The Magna Carta was pretty revolutionary in being a document that limits the power of the executive/gov, but our constitution definitely took it up a few notches with regard to putting the brakes on .gov power.
WRT the thread, I would have some serious concerns about a policy like this in the US. The big one that I am looking at is that you may be defacto compelling individuals to provide incriminating evidence against themselves in other, non sexual assault related, matters. It is a policy that is a powerful disincentive to reporting, potentially far more so than a disincentive to provide false reporting.