An example, I don't know of a Western style democracy, where it is legal for a cop to walk by your house, notice an open window, and crawl through it...
And then start searching your house, afterwards claiming "It wasn't breaking and entering! And all this stuff was just laying around!"
The law should be 100% the same for digital "stuff", in that, there needs to always, always, always be a justifiable reason, a warrant as well, before even the thought of a search can occur.
No back door usage, no "cyber tools", even if the phone is unlocked, on desk, nope! An open port(al), eg a window, doesn't give any reason for the search to be valid.
In terms of legalized back doors, and in encryption, that is 100% counter to all of the above. Case in point, if you want to know the content of someone's phone?
You can lock them up until they provide access -- after a court order requiring them to. EG, contempt of court, or some such.
(Even if the above doesn't jive in your legal locale, there are ways to enable the same. New tech, new laws, to enable the same concepts, and freedoms, and security, and privacy, our societies have known for centuries...)