HONOLULU -- A federal court judge on Friday upheld the U.S. Coast Guard's security zone for Kauai's Nawiliwili Harbor when the Hawaii Superferry sails into port.

Protesters filed for a temporary restraining order against the Coast Guard, saying limiting demonstrations to a designated area violated their First Amendment rights. The protesters and their attorney, Lanny Sinkin, argued that the Coast Guard's plans were excessive and limited their right to freely protest.

The court action comes after protesters first blocked the Superferry from entering Nawiliwili Harbor with protesters in canoes and on surfboards.

The Coast Guard then issued notice that it would set up a larger security zone around the Superferry that would essentially close off the harbor. Violators who violated that zone faced federal prosecution.

The Coast Guard said the zone was a matter of safety for the Superferry and the protesters. Officials said they wanted to avoid a potential accident in the water.

Judge Helen Gilmore ruled that the issue of safety was valid since protesters spoke about re-entering the water. She also said that the zone did not violate their First Amendment rights since there was a place on land designated for protesting.

"This is a challenging situation and we will respond as best we can, and in this instance, we feel the security zone is necessary," Coast Guard spokesman Lt. John Titchen said.

Sinkin said he plans to appeal the decision to the federal appellate court.

The Superferry has held off sailing back to Kauai until the legal matters could be sorted out.

Hawaii Superferry officials and a coalition of environmental groups have been testifying in a Maui court for four weeks on whether the vessel can sail into the Valley Isle's Kahului Harbor without an environmental survey.

Judge Joseph Cardoza could rule on the matter as early as Monday.

The final witness testified Friday. Hawaii Superferry President John Garibaldi testified his company has only $2.10 million in the bank and faces more than $$500,000 a week in expenses.

He has said if the company is not allowed to operate to Maui the Superferry could ship out to another location.

"If we can't operate while an (environmental assessment) is being prepared, or our operations are limited that we cannot make our business plan, it is an unfortunate circumstance for the state that they will lose their ferry service," Garibaldi said.

"I think they never should have operated or tried to operate, and if they really do care about the people of Hawaii then they should comply with our laws and stick it out," Superferry opposition's attorney Isaac Hall said.

The studies could take could take eight months or more. Judge Joseph Cardoza will hear final arguments on Monday..and could rule shortly after that.