Joe Public fights back...

Today in a Supermarket-begins with A, 4 letters. Guy in front of me going out sets off the Alarms. Security guard stops Him, and asks Him to step back into the store, I was behind and being a nosey s*d I hung around. Conversation roughly was this-

excuse me Sir, could I have a word?

no, problem, what's wrong?

you seem to have set off the alarm sir

why would that happen then?

that is what I'd like to find out

how?

could I see in your bag?

why?

i think there may be something in there

there is-shopping

something else maybe Sir

no there isn't 

could I look?

no

i need to Sir

are you a Policeman?

no Sir

right I'm going

(the Security guard held His arm as He tried to walk away)

thats assault, you are accusing me of theft, I'm not a thief. I have been here for 15 minutes I should be home by now. Either Phone the Police or I'm going.

at this point I lost interest as the crowd was beginning to get behind the Guy and complain to the Security guard.  Question from me- was the Guard or the Guy within the Law?