They can request and 99% of the time people just give it to them - all completely legal. However you can also legally refuse and then they need a warrant from m

They can request and 99% of the time people just give it to them - all completely legal. However you can also legally refuse and then they need a warrant from magistrate's court. I believe they can demand you don't destroy it though as that will be a criminal offence once they've told you.