Last month, Posner threw out a series of lawsuits between Apple and Google accusing each other of infringing smartphone patents.
He said he doesn't blame technology companies for going to court over patents because they are only using the competitive opportunities that the legal system offers them. He noted that for multibillion-dollar companies like Apple and Google, legal fees do little to deter patent suits.
"It's a small expense for them," Posner said.
He also noted that a device like a smartphone involves thousands of features that can all receive patent protection.
"You just have this proliferation of patents," Posner said. "It's a problem."