RIDGELAND -- Jasper County on Thursday filed its final argument against the S.C. State Ports Authority in the pending state Supreme Court lawsuit over who can build a cargo container terminal on the South Carolina side of the Savannah River.

For more than a decade, Jasper County officials have worked toward bringing a port to the county. When the county struck a $450 million development deal with a private port builder, the State Ports Authority responded with a lawsuit in the high court.

The State Ports Authority controls the fourth-largest cargo container system in the country through ports in Charleston, Georgetown and Port Royal. The agency's enabling legislation, penned in 1932, empowers the agency "to promote, develop, construct, equip, maintain and operate a harbor or harbors within this state on the Savannah River."

The county's attorneys maintain nothing in the legislation makes those powers exclusive, and under home rule -- a state law designed to move local government issues out of Columbia -- the county has the right to build.

"I guess that's really the issue, whether they have the superior right or we do," said Harry Butler, chairman of the State Ports Authority board of directors.

In Thursday's legal brief, Jasper County's attorneys, the Columbia firm of Lewis, Babcock & Hawkins, claimed the state agency's right is neither superior nor exclusive.

"Surely the (State Ports Authority) does not maintain that it has the exclusive authority to own and operate all watercraft and railroads in the State of South Carolina," the document states. "Jasper County's operation of a single terminal is not irreconcilable or inconsistent with any of the statutes creating the SPA."

The brief also attacks the State Ports Authority's law firm, Columbia-based Nelson Mullins Riley & Scarborough, for using a letter of support for a state-run port from six former governors. Richard Riley, a South Carolina governor from 1978 to 1986 and now a partner at Nelson Mullins, signed the letter.

"Obviously, the use by (Nelson Mullins) of a letter by recent former governors, including a partner in (Nelson Mullins), is entirely irrelevant in interpreting the intention of the General Assembly in enacting legislation in 1932," the brief states.

Kevin Hall, the partner in the firm working on the port issue, refused comment.