(Image credit: Courtesy barackobama.com)

The first family has yet to appear together on the 2012 campaign trail, but the faces of the foursome are now officially for sale in President Obama's campaign store.

A portrait of the president, first lady and their daughters taken in the Oval Office by an official White House photographer is prominently featured on Obama-Biden buttons for $5 apiece, and in an online campaign ad asking voters to "join our campaign."

It's the first time this election cycle that images of Sasha and Malia Obama have been used by the president's re-election team after years of careful control over their public use.

But more remarkable may be the legal and ethical questions raised by use of the photo, which was originally taken and published at taxpayer expense and for which political and commercial use is expressly prohibited.

White House spokesman Josh Earnest said in response to an inquiry from ABC News last week that the photos - which are freely available on the administration's Flickr website - are "basically items in the public domain."

"They cannot be used for commercial uses," Earnest said at a press briefing, "but we've also seen a number of political campaigns, certainly in 2010, that used … photos off the Flickr website and incorporated them into their television advertisements and other advertisements."

A disclaimer on the Flickr website underscores Earnest's point, warning that the photos "may not be manipulated  in any way and may not be used in commercial or political materials, advertisements, emails, products, promotions that in any way suggests approval or endorsement of the president, the first family or the White House."

But that appears to be precisely what the Obama Campaign has done.

For the online ad, the walls and furniture in the Oval Office appear to have been erased and replaced with a blue backdrop. On the campaign buttons, the distinctive striped wallpaper of the president's formal office are clearly visible. (See the official, unedited portrait HERE.)

Aides say the Obama campaign did not need to pay a royalty for use of the photo because it is publicly available.  But neither the White House spokesman on legal and ethical affairs Eric Schultz nor campaign spokesman Ben LaBolt would respond to questions about whether the sale of the image on buttons constitutes commercial use.

Richard Painter, the chief ethics lawyer for President George W. Bush from 2005-2007, said Obama was walking a fine line as his predecessors did but was probably immune from any legal or ethical violations in this case.

"Technically, the photos probably should not be used for such purposes without government approval because the government owns the photos," said Painter, "but many former government officials use their old official photos on websites offering their services in the private sector, or in company promotion materials."

"The past practice has been for Presidents to avoid mixing the official and political to the extent possible," he added. "Photos of the White House in campaign photos have traditionally been of the residence or - on Christmas cards - of the entire White House from the street.  The Oval Office has generally been avoided."

Obama is exempt as president from provisions of the Hatch Act, which restricts political activities of executive branch officials, limiting their use of government resources (including photos) and time paid by a taxpayer salary.

"It prohibits political activity that imposes an additional cost on the government," said Painter, now a law professor at the University of Minnesota, adding that the use of an existing official photo would not meet that standard.

The Obama campaign routinely hires outside media crews to film the president for campaign video commercials. The campaign also declined to explain why a family photo taken by an independently hired still photographer was not used in this case.