At 9:50 a.m. Wednesday, the Veterans Memorial Courthouse received two separate phone calls warning of a bomb inside.
Police decided to evacuate the building and sent in two K-9 units to search for explosives.
"We didn't find anything, and there was nothing suspicious," said Lansing Police spokesman Bruce Ferguson. "We are treating it as a bomb threat, we'll sent it to a detective, and we'll follow up on it."
Employees returned to work around 11:30 a.m.
Chief Judge R. George Economoy said he feels confident in the building's security.
"We practice evacuations all the time and today it worked. Our security here is very tight," he said.