What Extent Can Security Do At Malls?

So me and my friend got in an argument about stealing clothes from malls and stuff.. he always steals and I tell him it's stupid. We got into a conversation about the little security tags, he says if they ring as long as they don't see you stole something (ie you're wearing it under something etc) they can't do anything about it even if the alarm does go off.

Is this true? Really random, but I'm pretty sure they can do more otherwise everyone would just steal D:

By law, If they have reason to believe you are stealing, they can detain you for the police. An alarm going off would meet the legal requirement.

However, some stores have a more restrictive policy requiring an employee to witness the act. This is store policy only, and not the law.

I used to work at a shoe store. It was in an outdoor mall, so I'm not sure if things are different. But it is true-unless I see you put something in your purse/bag/etc., I can't touch you. And then once you go out that door, if I chase you and get hurt, the company insurance will not cover me. So basically, I can't stop you from leaving the store with the item unless I see you hide it...and even then, my manager would have to politely ask you if you had anything hiding and escort you out while I call the cops. We had a security officer, but honestly, I don't think he had any more power than we did.

Security can stop and detain you for a reasonable amount of time in order to call the police if they suspect you have stolen something. The alarms going off is a pretty good indicator that you're stealing. It's called the shopkeepers privilege.