The thing I always wonder about something like the government having the power to force people to decrypt data is what happens if the person claims they forgot their key. I could very much see this happening to me if I was arrested and my computers taken away only to months later be asked to unlock them.

Also what happens if the person used Rubber Hose cryptography. They could give up a key and the government gets some data but it would be impossible to know if they gave up all the keys. https://en.wikipedia.org/wiki/Rubber-hose_cryptanalysis