In his effort to push his health care overhaul, Obama invited doctors from all over the country to the White House as an audience for a speech. He really wanted to drive the point home that these were doctors who were supporting him, so they were asked to bring their white lab coats. Some forgot their coats and came dressed in formal attire. The administration decided to pass out lab coats to all of the people who forgot to bring their own.
http://www.nypost.com/p/news/national/white_house_botched_op_kTVWHZ3vEeRQbxCC0TNZHN (bold mine)
"A sea of 150 white-coated doctors, all enthusiastically supportive of the president and representing all 50 states, looked as if they were at a costume party as they posed in the Rose Garden before hearing Obama's pitch for the Democratic overhaul bills moving through Congress.
The physicians, all invited guests, were told to bring their white lab coats to make sure that TV cameras captured the image.
But some docs apparently forgot, failing to meet the White House dress code by showing up in business suits or dresses.
Perfunction compares the media reaction to Obama's actually staged photo op with the reaction to the mistaken belief that Bush had staged a photo op (http://perfunction.typepad.com/perfunction/2009/10/white-house-props-up-unpopular-policy-with-props.html).
The Rhetorican referred to it as "Obama’s Doc and Pony Show" (http://rhetorican.com/2009/10/06/obamas-doc-and-pony-show).