As its offerings grew, Robert Morris College -- the one based in Chicago -- decided the word "college" no longer fit the school's expanding role.

So its governing board decided July 18 to rename itself a university.

Sounded like a logical plan.

Except the name Robert Morris University, as Western Pennsylvanians know, already is attached to an institution in Moon. That school, which became a university in 2002, holds federal trademark registrations asserting that it, alone, has legal right to the name.

So Robert Morris in Chicago has filed a federal lawsuit in that city against Robert Morris of Moon, Pa. The former asserts that it, too, should be allowed to call itself Robert Morris University.

The complaint says that for decades, the two private, not-for-profit colleges carried the word "Robert Morris" without any confusion, and there is little overlap in enrollment, given the distance between them.

"Merely changing the generic portion of the Robert Morris College name from college to university is not likely to create any confusion that did not exist between the two institutions during the 40-plus years that they have both operated under the name Robert Morris," stated the suit filed Thursday in U.S. District Court for the Northern District of Illinois, Eastern Division.

Robert Morris University as of yesterday had not been served with a copy of the complaint. "We don't have any comment," spokesman Jonathan Potts said.

The suit says Robert Morris College was founded by the son of an official of what is now Robert Morris University. The suit says the college, , which was chartered in 1965, initially was a branch of the Pennsylvania school but for decades has been a separate entity.

Officials with the college, whose Web site put enrollment at 6,500, declined comment yesterday. Moon's Robert Morris has about 5,100 students.

Colleges are highly protective of their identity. That said, some schools co-exist with similar, or even identical, names.

The University of Notre Dame is adjacent to South Bend, Ind., but Notre Dame College is in South Euclid, Ohio. The University of Miami is in Coral Gables, Fla., while Miami University is in Oxford, Ohio.

Someone mentioning Westminster College could mean the one in New Wilmington, Pa., or Salt Lake City, Utah, or Fulton, Mo. There's even a Westminster Choir College in New Jersey.

"We've shared the name with some of them for 155 years," said Mark Meighen, spokesman for the college in New Wilmington. "We're used to fielding requests from people looking for the Westminster in, say, Missouri. We send them along the correct information. The other schools do the same for us."

But things can become contentious, said Sheldon Steinbach, higher education law specialist and retired general counsel with the Washington, D.C.-based American Council on Education.

Once in court, the disputes can turn on "who was first to file and protect the name," he said.

The lawsuit says Robert Morris College gained university status in 2005 and was told in June by the Illinois Board of Higher Education that the name change required proof that the college owned the name. In addition to Chicago, the school has six other locations in the state.

Both schools are named for the man who was among the wealthiest signers of the Declaration of Independence. Mr. Morris is credited with helping to finance the Revolutionary War and was a key founder of the financial system of the United States.