Restrictions with respect to former employees

(a) No former employee of the Commission or the Commissioner (including a member of the Commission or the Commissioner) shall appear before the Commission as an attorney or other representative for any party in any proceeding or other matter, formal or informal, in which he participated personally and substantially during the period of his employment. (b) No former employee of the Commission or the Commissioner (including a member of the Commission or the Commissioner) shall appear before the Commission as an attorney or other representative for any party in any proceeding or other matter, formal or informal, for which he was personally responsible during the period of his employment, unless 1 year has elapsed since the termination of such employment.