Bloomington emergency room physician David Gill, his campaign committee and Washington-based Citizens for Responsible and Ethics – or CREW - are suing the Internal Revenue Service.

Melanie Sloan, executive director of CREW, says federal law should keep groups like American Action Network from running campaign ads. American Action Network spent about $1.5 million on negative ads against Gill during last year’s General Election.

Sloan says federal law outlines that 501-c-4 groups must be operated “exclusively for social welfare purposes”, but IRS regulation says those groups only have to be “primarily engaged in social welfare.”

“And there's a big gap between "primarily" and "exclusively" and it's exactly that gap that these 501-c-4's have exploited," says Sloan. "They say while they're engaging primarily in social welfare activities, at least part of their time and budget can be spent on political activities. That, to us, seems to fly in the face of the federal statute."

Those groups also don’t have to disclose their donors. Sloan says other filings have accidentally revealed Aetna Insurance and the Pharmaceutical Research and Manufacturers of America made donations toward ads last fall.

“Those huge donations were contributed to the American Action Network which then ran ads against David Gill trying to paint him as a mad scientist and opposed to Medicare," says Sloan. "But really David Gill has been in favor of Medicare for all and he's in favor of insurance coverage that Aetna and Pharma were opposed to. So, it seems that the real reason these negative ads were run against Dr. Gill was because of his positions on healthcare."

Gill says he’s not trying to take away from anyone’s freedom of speech.

“They shouldn't hide behind some dark cloak and try to fool people," says Gill. "They should be out there saying 'We're Aetna Health Insurance and we don't like Dr. David Gill. A man who stands for a national health insurance program which would stand to do away with the obscene profits that are made today by health insurance companies and drug companies."

Dan Conston, communications director for American Action Network, told WLDS-WEAI News in an e-mail, “The American Action Network's significant advocacy efforts for center-right causes are well-established, and the Network continues to keep its primary focus on those non-electoral activities, as required by law.

"The Courts and the IRS have rightfully concluded that a group like ours should have the right in a limited fashion to advocate for candidates that share our beliefs as well as the beliefs themselves."

Sloan says there’s no precedence for litigating the IRS rule.