Assume we live in a world where we either have -Devices which

>>1369849

What a stupid question. No, obviously.

>>1369849
It isnt ethical to arrest a person for a crime they have not yet commited, but it is ethical to prevent the crime from occuring. For example,
>Billy works for a business
>Crimebot reads the future and sees that Billy will commit tax fraud in the future
>Crimebot representative tells Bill not to cheat on his taxes because it will be caught
>Bill decides not to commit the fraud
However, if Bill still commits the tax fraud, it is perhaps on more ethical grounds to arrest him because Bill knew that Crimebot knew he was going to commit fraud. Preventative Crime thought experiments should focus on just exactly what the name implies, preventing crime.

If your into anime, you should check out Psycho-Pass. It deals with this exact issue.
In the show, people have a "crime coefficient". This number reflects how likely it is someone will commit a crime. If it's high enough, police are permitted to kill on site.
Obviously, this is NOT a good idea. As one can see in the show, people fucking obsess over their crime coefficient. It simply adds to the stresses of everyday life, knowing that at any time you could be imprisoned or even killed just because your number rose, even if you really never wanted to hurt anyone.