The Department of Labor's (DOL) finalized fiduciary rule "exceeds the Department's statutory authority and is arbitrary, capricious, and contrary to law," according to a lawsuit filed against the DOL and Labor Secretary Thomas Perez in U.S. District Court for the northern district of Texas.

Named plaintiffs in the suit are the U.S. Chamber of Commerce, Financial Services Institute, Financial Services Roundtable, Insured Retirement Institute, the Securities Industry and Financial Markets Association, and several Texas-based business interest groups and affiliates of the Chamber of Commerce.

In vastly expanding the definition of fiduciary under the Employee Retirement Income Security act to all advisors, broker-dealers and insurance companies servicing IRAs and tens of thousands of 401(k) plans with less than $50 million in assets, the DOL is effectively rejecting long-standing securities laws, and encroaching on responsibilities Congress has mandated to the Securities and Exchange Commission, plaintiffs claim.