PORTLAND, Maine — The attorney for the Maine Department of Corrections said Tuesday that there would be “real consequences” if the Maine Supreme Court does not overturn a lower court ruling that she said would restrict when the department places a prisoner in segregation.

The argument came Tuesday morning in the appeal filed by the state in the case of prisoner Franklin Higgins.

Higgins had challenged in court the right of corrections officials to place him in administrative segregation based solely on an indictment. Higgins was indicted in October 2011 for murder in connection to the beating death of fellow prisoner Lloyd Millett at the Maine State Prison.

That charge was later dropped and Higgins was indicted in April 2012 for aggravated attempted murder in connection to Millett’s death. Higgins was acquitted by a Knox County jury in March 2013 after the defense argued that the death was in self-defense.

Higgins was held in administrative segregation for about two years, said Kevin Decker, Higgins’ student attorney from the University of Maine School of Law during arguments made Tuesday before the state’s high court.

Decker said the Department of Corrections was — by basing its decision on the murder indictment — outsourcing its authority to place prisoners in segregation to a grand jury. He said because grand jury proceedings are secret, a prisoner cannot challenge its findings if the Knox County Superior Court ruling was overturned.

The lower court ruling found that an indictment, which determines whether there is probable cause for a charge to levied, was insufficient and that a higher standard such as preponderance of the evidence is needed when placing a prisoner in segregation, Department of Corrections attorney Diane Sleek told jurists.

Some of the court’s justices challenged Sleek’s assessment and asked whether the Superior Court judge was simply saying an independent review should be undertaken by the department to determine whether to place a prisoner in segregation.

Sleek argued that even though Higgins is no longer in segregation, it was important for the department to know whether it can rely on an indictment against a prisoner for a violent crime within the prison when it makes a decision on placing a prisoner in segregation.

The lower court ruling could interfere with police investigations if the department must conduct its own investigation immediately after a violent act occurs, Sleek said, suggesting that the department might be forced to release a prisoner into the general population and place other prisoners at risk.

Further, if the lower court ruling is not overturned, Higgins could use that ruling to seek damages in a civil lawsuit about being improperly kept in administrative segregation, Sleek said.

Higgins is serving a 45-year prison term for the Feb. 27, 1999, murder of 40-year-old Katherine Poor of Kenduskeag.