Pensioners and city workers chanted "Hands off our pensions" and "Make the banks pay."
Lawyers representing the city and state and union workers argued about whether Detroit's historic Chapter 9 bankruptcy filing allows government officials to cut pension payments for retired workers.
Sharon Levine, a lawyer representing the American Federation of State, County and Municipal Employees union, said she plans to argue during the bankruptcy proceedings that cutting pension payments for those already retired and reliant on them is illegal.
"The retirees are very concerned about what's going to happen here; they're scared," she said
Levine said the pensions are typically $18,000 a year or less.
"This is a very, very difficult situation," she said.
Protesting retirees contended that the city's dysfunction shouldn't be workers' responsibility to fix.
"All the mismanagement, all the corruption, it's not our fault," said Alonzo Griffin III, 63, a retired city worker. "We work the streets, we do the sidewalks, the garbage; we do the best we can."
Testimony is expected from the city's emergency manager, Kevyn Orr, and other consultants.
Levine said she plans to call retirees to testify about the potential impact of cuts to their pensions.