PORTLAND — Maine's highest court ruled Thursday that settlement documents between a corporation, the city of Bangor and the state Department of Environmental Protection are public records subject to disclosure requirements of the Maine Freedom of Access Act.

In a unanimous opinion, the Supreme Judicial Court upheld a lower court opinion that the documents should be made public.

The case dates back to 2002, when the DEP designated a cove on the Penobscot River in Bangor as a hazardous substance site because it was contaminated with coal tar.

The city of Bangor sued Citizens Communications, a Connecticut-based company that owned the former Bangor Gas Works, which was allegedly responsible for the contamination. Claims between the city and Citizens eventually were tried in U.S. District Court, with the court ruling that both entities were partially liable for polluting the cove.

Following the court's finding, the city, the DEP and Citizens held confidential negotiations to develop a remediation plan and exchanged draft consent decrees.

During negotiations this year, two other companies filed a Freedom of Access requests for the consent decrees and other related documents.

The state agreed to provide the documents, but Citizens filed a lawsuit in Superior Court to stop the disclosure. A Superior Court judge ruled that the documents should be made public, but stayed its judgment to allow Citizens to appeal.

The supreme court rejected Citizens' arguments that the records should not be made public.

The opinion states that the records do no fall within the "privileged records" exception to the Freedom of Access disclosure requirements.

Justices also rejected the argument that there was an attorney-client privilege during Citizens' communications with the DEP and the city of Bangor. The court said attorney-client privilege does not protect communications between adverse parties on opposite sides of the bargaining table.

"The argument that adverse entities have shared interests merely because they are willing to negotiate a settlement is an attempt to distort the scope of the attorney-client privilege," the opinion said.