Three more plot holes

Rating: 6/10 (23 June 2002)

***SPOILERS*** ***SPOILERS*** Sort of a *SPOILER*
I only looked back around 40 comments, so maybe this was mentioned a long time ago, but:
1) (This one really bugs me) John Anderton had a witness (Agatha) who could give compelling evidence that he did not kill Leo Crowe and that he could not have killed Witwer because he was with her the entire time during which the crime occurred. In addition, there is no way that John could have had the gun he supposedly used to kill Witwer because it was found (with fingerprints intact) at the scene of the first 'crime.' Even if pre-crime convictions are somehow completely devoid of any due process (see #2), John's crimes would not count as pre-crimes and he should have a full-fledged trial where these issues would come out.
2) The link between being able to tell the future and the complete lack of due process doesn't make sense. The legal status of the pre-cog's evidence even if they were never wrong, would be something like 'eye witness' evidence, leaving the pre-murderer all of the usual protections of the law including plea-bargaining down to manslaughter, justifiable homicide, and temporary insanity. It might be like someone telling the police about a murder that is planned (or in progress). These situations have clear precedents in law. Further, even if you did find that pre-crime was not 100% accurate, it could probably still be used effectively in crime prevention without junking the entire project. Why not just prevent the murder without locking up anybody?
3) The supposed infallibility of the pre-crime unit doesn't make sense. In every case we saw it in action (the scissors at the beginning, the suicide of Leo Crowe, and the near-murder of John Anderton) they either arrived too late or almost too late. After all, if you're given 10 or 15 minutes to find a murder happening somewhere in DC, what are your odds of actually stopping it in time? I imagine that they'd be pretty low, and that's how they're portrayed by the film as well.