DrCaleb DrCaleb:
No, it's always illegal.

Unless like Tricks, you are hired to break in, and there there is only a limited and pre-defined scope to that break in.
Don't get me wrong, I've fudged stuff to get around restrictions at companies.
I had a retailer that wouldn't let me order a part to pickup in store at the store near me, because it wasn't in stock. Apparently they changed the policy of shipping to the store and allowing for pickup. So when I put through the order, I intercepted the post packet, changed the store parameter to the one I wanted, and sent it on through.
Surprisingly it actually worked. The order got submitted, and a friend of mine working for the company confirmed that it was put through to ship to the location I wanted.
Then I bought it elsewhere because fuck them.