The country’s largest business lobbying group has selected Sullivan & Cromwell as outside counsel in its federal challenge to the Federal Trade Commission’s ban on noncompete clauses. Meanwhile, former Department of Labor Secretary Eugene Scalia and colleagues from Gibson, Dunn & Crutcher entered appearances for tax services firm Ryan LLC in the first federal action filed against the commission this week.

Lawsuits filed Tuesday and Wednesday by Ryan and the U.S. Chamber of Commerce, respectively, challenge the FTC’s newly published rule, unveiled Tuesday, that seeks to prohibit companies from enforcing noncompete agreements in most cases.