[nawtacawp]

First, it would vary by phone -- but if LEO is requesting your phone and do not have a warrant (yet), they could still seize the phone citing exigent circumstances. The exigent circumstances being that if they left the phone in the custody of the subject, then they will likely delete the contents or at least could delete the contents. Once the phone is in LEO possession then they can take the time to apply for a warrant to search the device.

So -- if you get to the point of LEO requesting your phone and you have data on your phone, then it is too late.