[quote:8cf65140dc="Pixel"]a professional locksmith might carry a set of lock-picks on the way to a job where he had to get someone into their house when they had locked themselves out and left their keys inside - perfectly legitimate - but someone without that professional background, found with a set of lock-picks - especially at night - would almost certainly find themselves in court and convicted in very short order. [/quote:8cf65140dc]

This actually works both ways.

The father of one of my highschool friends owned a bikeshop.
After 2 robberies (Money, not the bikes :-) ) he used to have a bat behind the counter.

A friendly policeofficer explained that, if he would beat someone up with it, even if they were robbing him, he could be guilty of a crime, because the bat could only be in the shop for that....

He advised him to switch the bat with a "Spoke spanner", because that way it could just be "at hand", especially in a bikeshop.

A spokespanner is a wooden thing, the size of a small bat, with some iron thingies at the end...