How can you find out the registered owner by plate or VIN?

How can you find out the registered owner by plate or VIN?
This is illegal unless you have a "legal reason" and can convince the government.
Each place has different requirements for this.
Where I am our company has to be registered with the government, bonded and have a legal reason to know the info, all of this has to be applied for and approved before hand.
Then if a vehicle is left on our lot we can trace the owner and charge towing or storage fees. We are a licenced storage facility.