Decision-making Commission personnel, as defined in Sec. 3001.7(a), shall not, either in an official or unofficial capacity, participate in any ex parte communication--either oral or written--with any person regarding (1) a particular matter (substantive or procedural) at issue in contested proceedings before the Commission or (2) the substantive merits of a matter that is likely to become a particular matter at issue in contested proceedings before the Commission. A particular matter is at issue in contested proceedings before the Commission when it is a subject of controversy in a hearing held under 39 U.S.C. 3624 or 3661(c). However, this section does not prohibit participation in off-the-record proceedings conducted under regulations adopted by the Commission for hearings held under 39 U.S.C. 3624 or 3661(c). [45 FR 65581, Oct. 3, 1980]