The specific fiduciary standards for registered investment advisors could be different under the final version of the Labor Department’s proposed rule than it is under existing Securities and Exchange Commission mandates, according to a former director of the SEC’s Division of Investment Management.

Norm Champ, who made the comments after speaking at the IA Watch compliance conference in Washington, D.C., said that the obligation for fiduciaries to work in the best interests of clients does not come from SEC rules but from a 1963 U.S. Supreme Court decision in the case of SEC vs. Capital Gains Research Bureau.

If the SEC comes out with a written proposal for a fiduciary rule for broker-dealers, as the agency’s chair Mary Jo White has said she wants, the regulator would also likely come out with written “best interest” guidelines for advisors as well, Champ predicted.

Champ is now an attorney with the New York office of the law firm Kirkland & Ellis.