I read on here that taking ativan (lorazepam) , even with a valid prescription will result in a dui . i's this true?

You betcha!: It could, if you got pulled over for erratic driving, or if you got pulled over for something else and the officer suspected you were shlogged-out on something. Best not to drive if you've just taken something like that or for at least 3-4 hours after or if you feel at all buzzed. Ideally, best to wait after sleeping a full night (e.g. to go to work in the morning).

DUI: Any drug, prescribed or not, which impairs your ability to safety operate a motor vehicle puts a person at risk for a DUI charge.

Yes and no...: Yes & no. Refer to your local/state laws. Generally, if you are taking the medication specifically as prescribed, and your healthcare provider feels you are safe to operate vehicles, then you are OK. I would advise getting a document from your prescriber confirming this. That said, don't think you are safe to drive with any alcohol in your system. Even under the legal limit, you're compromised.