[NittanyLion]

I understand the need to protect against police abuses but do we let the child molester, islamic terrorist, rapist or other criminal go and feel superior about it because someone errs?

Yes, because as a matter of public policy the system of incentives currently in place offers the greatest level of protection to the most people.

[misterrob]

There are situations when there is abuse and then there are mistakes. Kicking a scumbag loose because someone didn't update a database is a lot different than random stop and search, police checkpoints and kicking down a door without probable cause.

All Scalia is questioning if we have to automatically exclude inadvertent mistakes.