The City of Gretna operates under the "Lawrason Act" which can be found in the Louisiana Revised Statutes 33:321-481.
R.S. 33:321-481, commonly known as the Lawrason Act, are the laws governing the operation of the incorporated municipalities in this State. It explains how a municipality is considered a city, town or village. It covers the qualifications, duties, powers, and selection by either election or appointment, and the functions of each officer (mayor, board of aldermen, clerk, treasurer, marshal, mayor's court). It also details the levying and collection of taxes and expenditure of funds.