The Maine Supreme Judicial Court on Thursday upheld the city of Portland’s approval of a project to build more than 200 units of senior housing on Steven Avenue.

At issue was a July 2015 decision by the City Council to rezone 7.5 acres that include the historic Sisters of Mercy convent and athletic fields used by the former Catherine McAuley High School, now called the Maine Girls’ Academy. The land was changed from a low-density residential zone for single-family and smaller multifamily homes into a higher-density zone that would allow nearly 250 units of housing.

A group calling itself the Friends of the Mother House, along with Barbara Weed and Raymond Foote, sued the city three months later, arguing that the city did not follow proper procedures and that the rezoning was not consistent with the city’s Comprehensive Plan, which guides land use decisions.

The group lost its case in Superior Court, but appealed that decision to the Law Court, which heard arguments on Nov. 10.

“(The) Friends did not meet its burden to prove that the Council’s action rezoning part of the Motherhouse property to allow the development of senior housing – while retaining the high school and St. Catherine’s Hall in their original zone – was not ‘in basic harmony with the comprehensive plan,’ ” the ruling states.

Sea Coast Management and the Developers Collaborative are planning to restore the Motherhouse, originally built in 1908, and convert it into 88 units of senior housing. Additional residential buildings up to 55 feet tall could be added at the rear of the property located at 605 Stevens Ave.