HELENA - Montana's Legislature voted unanimously back in 2007 to resist the federal REAL ID law, which sets standards for the issuing of drivers' licenses and state identification cards.

But the law's been moving ahead anyway - with possible consequences ahead for Montana. Residents could be restricted from boarding commercial airliners as early as 2016 if the state doesn't make some changes - or if the U.S. Department of Homeland Security doesn't grant an extension.

What's wrong with Montana licenses? A letter last month from Homeland Security outlines 25 regulations it says Montana doesn't meet.

Aamong other things, DHS wants Montana to verify so-called Social Security numbers and so-called source documents - like passports and birth certificates in ways suitable to DHS; keep digital copies of those source documents for 10 years; report back to DHS on the ability of the cards to resist forgery; and plenty more.

Governor Steve Bullock, a Democrat, responded to Homeland Security on Friday, noting that the costs associated with the program, and the potential privacy problems, are unacceptable in Montana.

He said he'd ask the Montana Department of Justice, which oversees driver's licenses, not to take any steps that would penalize Montanans.

Attorney General Tim Fox, a Republican in charge of the Justice Department, said in a joint statement with Bullock that Montana's licenses are among the most secure in the nation.

"The amount of time and expense and training that would go into having DMV staff verify every birth certificate, every Social Security number, every utility bill that Montanan would want to use to prove his or her identity, to get a driver's license, would costs a significant amount of money and is a real burden for the state of Montana," said Niki Zupanic, public policy director for the Montana chapter of the American Civil Liberties Union.

What's more, the card itself would have to include what's called "machine-readable technology," like a bar code or something more.

"Well, that may be convenient for TSA agents but it's also really convenient for identity thieves," Zupanic said.

Unless it grants an extension, DHS could start restricting Montanans' access to certain federal facilities starting this year.