HumaneWatch.org, a project of the Center for Consumer Freedom, released a video interview with a former undercover investigator for the animal liberation group Humane Society of the United States (HSUS). Gestation stalls, or individual maternity pens (IMPs), are used to house pregnant pigs. IMPs provide for individual care and feeding while preventing the fighting that occurs when pregnant sows are housed in groups. Mainstream veterinary groups support maternity pens as a humane housing option. However, HSUS has been lobbying legislators to ban these gestation pens and are pressuring food companies to only source pork from farms that use group housing of sows.