La. R.S. 11:1118

Notwithstanding any other provisions of law to the contrary, any active contributing member of this system who becomes engaged in employment which would normally require him to join and become a member of any other public retirement system or fund shall have the option of joining and becoming a member of such other public retirement system and thereby cease to be a contributing member of this system. If he terminates the employment which makes him eligible for membership in another public system or fund he shall again become an active contributing member of this system as a condition of employment for as long as he is employed in a position which makes him eligible for membership in this system.