I'm not a lawyer and the proper answer is likely state-dependent, but why not? It's well established that with an appropriate warrant, LEO have always been abl

I'm not a lawyer and the proper answer is likely state-dependent, but why not? It's well established that with an appropriate warrant, LEO have always been able to come into your house without telling you and add hidden surveillance bugs to listen on your communications; they have always been allowed to physically modify or replace your phone (e.g. physical phone wiretaps a century ago); Electronic Communications Privacy Act reasserts that this applies also to electronic surveillance and digital communications; so (as a non-expert) I don't really see why that wouldn't apply to smartphone exploits as well. We do see exploits being applied to devices in LEO possession (e.g. https://www.theverge.com/2021/4/14/22383957/fbi-san-bernadino-iphone-hack-shooting-investigation https://www.theverge.com/2021/4/14/22383957/fbi-san-bernadin... for one random example) to recover evidence. The main restriction is the constitutional limits of 4th amendment which requires specific warrants for each case - which is a significant practical obstacle, so the circumstances in which warrantless wiretapping is permitted (e.g. by PATRIOT act) is a contentious issue; however, it's not relevant if a proper warrant is obtained.