> Should the police be able to access the Signal messages of someone they apprehended at a murder scene wherein other suspects fled the scene, and are therefore likely the suspects accomplices?

> Likely yes. Or at le[a]st, most people would agree with it both in the pragmatic sense, and also the Constitutional sense.

Sure, but that is not the question. The question is: should Signal be forced to implement its software in a way that allows the police to access its messages?

Likewise, everyone also agrees that in person surveillance is in general legitimate, but that doesn't mean that we all agree that the government should be able dictate burdensome measures on third parties to make it easier to perform this surveillance: say require that the friends of the suspect keep notes on his whereabouts. Changing its architecture would cost Signal a lot of money and good will, and the suspect would probably not be very happy that his friends ratted him out as well.