Updated 11:46 am

The Obama campaign is not employing the widely used credit card address verification system to check whether the address submitted by a donor matches the address tied to the credit card, an omission that might allow supporters to use a fake identity when contributing.

The practice could potentially allow donors in possession of illicitly obtained credit card numbers to exceed the campaign limit, and to permit overseas supporters to contribute.

The Mitt Romney campaign does require use of the system and asks the donor to include the three or four numbers- sometimes known as the “CVV” code – on the back of the card. The code helps determine whether the donor is in possession of the card.

The Obama campaign donor page does not have a box for entering the CVV code and does not appear to reject donors who lists addresses different from those attached to the cards.

It’s not clear if the Obama campaign has some kind of backup system that would mitigate the need for the address verification system. The campaign did not respond to a request for comment. But what is clear is that it is failing to use the most basic tool employed by businesses and groups around the world that accept credit card payments online.

John Hinderaker over at Power Line blog tested the Obama system, donating under the name “Illegal Contributor” and listing his address as “Cell Block 13″ in the State Penitentiary.” He said his employer was the “Minnesota Penal System” and listed his occupation as “inmate.”

Not only was his $3 donation – made with his real credit card number – welcomed, but he was asked to set up his own grassroots fundraising page so he could induce others – why not the entire cell block 13? – to contribute as well.

Trying the same experiment over on the Romney website likely would not work, because the address verification system would determine that there is no “Illegal Contributor” living at the State Penitentiary associated with the credit card.

The blog Hot Air reported in 2008 that the Obama campaign was doing the same thing then.