Institutional Shareholder Services Inc. (ISS), a proxy advisory firm based in Maryland, is turning to the courts to challenge guidance issued by the U.S. Securities and Exchange Commission (SEC) in August that curbs the role of proxy advisors.

ISS announced that it has launched a lawsuit in U.S. district court seeking relief setting aside the SEC’s new guidance, which, among other things, declares that proxy voting advice constitutes a “solicitation” under federal rules.

In its lawsuit, ISS says that the guidance was adopted improperly, that it is “arbitrary and capricious,” and that the SEC exceeded its authority in adopting guidance that effectively regulates the provision of proxy advice.

ISS also states that the guidance will harm its business by creating added legal and compliance costs to comply with proxy solicitation requirements, and “opens the door” to both SEC enforcement action and lawsuits from issuers that disagree with its client voting guidelines.

“After careful review of the August guidance, we are deeply concerned that it will be used or interpreted in a way that could impede our ability to deliver our data, research and analyses in an independent and timely manner,” said Gary Retelny, president and CEO of ISS, in a statement.

“We believe litigation to be necessary to prevent the chill of proxy advisers’ protected speech and to ensure the timeliness and independence of the advice that shareholders rely on to make decisions with regards to the governance of their publicly traded portfolio companies,” he added.