In Retail
You will get many types of guards who will do all sorts of things, some get away with it some don't, bear in mind many scallywags know as much about the law as we do !
In general when a shoplifter gets caught, we can ask them to empty the bag out to show what they have stolen, or they carryout a self search and then the Management more often than not make a decision on recovery or call the Police, some stores set a £££ limit some call for everything. WE CANNOT remove items from the Bag, or the Person only Police have the Powers to to do so, If the shoplifter refuses to show us what they have, it will strenghen the case agaisnt the Offender when the Police turn up.
When the EAS goes off we usally ask the person if they have bought anything that may have a tag on it and if so we would go to customer services and they would check agaisnt the receipt and de tag etc. Or in other cases they have items from other shops.
I know in Night clubs that a condition of entry, is you will be searched ranging from pat down to bag search, this is mainly due to the drug and weapons culture we live in today. and this should be clearly stated and displayed before entry to the clubs.
In most and all shops I have ever been in I have never seen a sign that says you or your bags may be searched on entry or exit of these premises, "I am not saying that these don't exist but I've not seen any down this way.
So again if you have no signs indicating what may happen in your store you should not be searching peoples bags, you should ask them to empty, then get the Police if they refuse to show.
Basha72