Warrants are not supposed to be impossible. If you cannot ID a person in todays world you cannot gain a warrant. But then, that is what you really seek huh?
I will ask you too and a bit more specific this time.
How can one gain a warrant in today's world without establishing the identity of the person one seeks to gain a warrant against?
The same way they always did. Stakeouts, eyewitnesses, and plain old-fashioned gumshoe work and boring waiting.