I am not sure how this can be implemented effectively in a globalized world! Lets say we take John McCain's advice and corporations give america a back door to

I am not sure how this can be implemented effectively in a globalized world! Lets say we take John McCain's advice and corporations give america a back door to read encrypted data, what would other countries do? Would they make laws forcing corporations to give back-doors on the encrypted data as well? Eventually, one of these countries could sell that information to unscrupulous hackers? Also, such a mechanism will only catch unwitting gmail like app using terrorists (assuming google co-operates with USA). I would guess vast majority of terrorists will still encrypt the data themselves without relying on underlying app to do so?