Canon 33

RETIREMENT FROM JUDICIAL POSITION OR PUBLIC EMPLOYMENT. A member shall not accept employment as an advocate in any matter upon the merits of which he has previously acted in a judicial capacity.

A member, having once held public office or having been in the public employ, shall not after his retirement accept employment in connection with any matter which he has investigated or passed upon while in such office or employ, adverse to the interest previously represented by him while in such office or employ. A public officer should endeavor so to discharge his official duties that his employment after the expiration of his term of office should be unnecessary.