I have a bottle of lorazepam 1mg that expired march 2012 (4 1/2 years old). are the still safe to take?

Probably not: Depending on when the bottle was first opened and how & where it has been stored, it's likely that the medication is not as effective as when first obtained. If it's been stored in hot or damp conditions (e.g bathroom cupboard) it may have decomposed so may contain unwanted products of that process. Safest thing to do is to return to your pharmacy for them to dispose of.

Probably safe: Pharmacies typically provide an expiration date a year past the date of fill. However, this does not necessarily mean that the medication is harmful beyond this date. Medications may not be as effective the longer they are on the shelf. So, probably safe to take but better to get a new prescription so that you know how much medication you're actually getting. Return the old stuff to a police dept