SPRINGFIELD, Ill. (Legal Newsline)-In what is shaping up to be an epoch legal battle between Great Lakes states, the Illinois attorney general Tuesday urged the U.S. Supreme Court not to change its mind and order the closure of Chicago-area shipping locks.

Michigan Attorney General Mike Cox, a Republican, has been doggedly seeking closure of the shipping channels to prevent the massive bighead and silver carp from migrating into the Great Lakes, where the invasive species could ravage the regional sport- and commercial-fishing industries.

In court papers filed Tuesday, Illinois Attorney General Lisa Madigan, a Democrat, said Cox's most recent pleas to close the locks are unfounded.

"The only 'new' developments are the defendants' ongoing efforts to combat the carp's progress and federal executive and congressional interest and involvement in the issue, but these measures undercut Michigan's renewed motion," Madigan told the nation's highest court.

Cox, who is running for governor, first sought the locks' closure in December. He asked, at the time, for the high court justices to order a temporary injunction that would close the locks until the Asian carp threat could be dealt with comprehensively.

The justices declined. Shortly after, Cox filed a motion asking the court to reconsider, citing scientific reports that genetic material from Asian carp was detected in Lake Michigan. In court papers, Cox accused the U.S. Army Corps of Engineers of withholding the reports until after the court had denied his request for an injunction.

For its part, the White House has urged the Supreme Court to allow the locks to remain open. U.S. Solicitor General Elena Kagan, who represents the Obama administration before the high court, has said in court papers that Cox's plan would impede commerce and compromise public safety by interrupting U.S. Coast Guard activities in the region.

The case is being heard by the U.S. Supreme Court because legal disputes among states are adjudicated by the high court. In seeking the preliminary injunction to close the locks, Cox reopened a 1966 U.S. Supreme Court case over the Chicago Sanitary and Ship Canal and the threats plaintiffs say it poses to the Great Lakes.

From Legal Newsline: Reach staff reporter Chris Rizo at chrisrizo@legalnewsline.com.