OK by now some regulars here might know of my opinion that Voyager is my least fav series, but that Voyager spawned quite a number of ST's best eps of all time, case in point: Relativity!! I love this episode, right from the time travel elements , down to the starship (a UFP timeship!) and Braxxton's dialogue.

But even with the ability to go through time, it seems to me like one would still have a large number of choices for any set of variables. Therefore you can't simply arrest someone for a crime they haven't comitted yet, because that might not be the only way to prevent it. Kind of like how Picard said in AGT that he preferred to look on the future as not being set in stone, and to not assume he would become ill just because Q showed him that in one future.