What would be unethical, according to Blakely, would be if the doctor took up a political discussion with the patient in the examining room. Hanging a sign outside his door is a matter of free speech, she said.
The American Medical Association, which offered "qualified support" for Obama's healthcare bill, has a code of medical ethics that is not enforceable, but gives doctors guidance on various issues of patient care.
The first line of its code emphasizes that physicians enjoy the same freedom of speech as other Americans, "but under no circumstances should different political views interfere with the delivery of care."
According to AMA Code of Medical Ethics, "It is laudable for physicians to run for political office; to lobby for political positions, parties or candidates; and in every other way to exercise the full scope of their political rights as citizens."
"Physicians will express their views to patients or their families," the code reads. However communications about political matters must be "conducted with the utmost sensitivity to patients' vulnerability and desire for privacy."
These conversations are also inappropriate when patients or their families are "emotionally pressured by significant medical circumstances."
Dr. David Cronin, associate professor of surgery at the Medical College of Wisconsin, who trained in medical ethics at University of Chicago, said under federal law doctors cannot discriminate on the basis of race, color, creed or sexual orientation.
As for voting habits, "that's an interesting question," he said.
"It might be quite distasteful to say, if you voted for Obama's health plan there is no need to come to my office," he said. "I don't like it, but is it illegal? I don't think so."
Grayson he is supporting Chapman, even it means filing a lawsuit if Cassell is in violation of federal discrimination laws.
"I think that the sore losers are out in force," he said. "What they don't understand is that we've decided as a country to make sure that people can see a doctor when they need to. I don't know what they are so upset about. I really don't."