This is of course a wild hypothetical question and there is probably no good answer. Suppose a police force obtained a time machine and wanted to use this to obtain evidence to investigate crimes and convict criminals. Would they be able to use this evidence in court? I am thinking about a few ways the time-travelers might obtain potentially tainted evidence:
- The officers have obtained a search warrant to search a certain place, perhaps a suspected hideout that a suspect may have used in the course of planning or committing the crime. Currently, there is nothing incriminating in the hideout, but the officers use their time machine to go back to a time, before the warrant was issued, and find incriminating evidence. Would this evidence be admissible? Similarly, could time-traveling officers follow a suspect with no probable cause obtained before the crime if they know from the future that this is a person of interest?
- Would anything stop these officers from traveling back in time, watching the crime as it happens, and using either their eyewitness testimony or a videotape as evidence? I'm assuming for now that they're not messing with the past by trying to interfere to stop the crime.
Thank you for entertaining this silly question.