I haven't given this topic a whole lot of thought.. but my first instinct is that not all scenarios are equal.

I would easily agree that random mind scanning is bad. If you are just walking through an airport and there is a machine reading your thoughts and you can be held accountable for those thoughts, that is bad.

However, if you are suspected of committing a violent crime, and they can read your thoughts to determine your guilt, I'm more open to that idea. However, the technology would have to be 100% flawless. As far as I know most states still do not allow any form of lie detector test to be admissible as court evidence due to unreliability.

Also, if someone is already in prison and being evaluated for early release, I could be persuaded that mind scanning might be viable in that case.

Totally random or doing it to everyone seems unquestionably bad.. but targeted scanning for cause could be reasonable -- again depending on the accuracy of the technology.