Universal Music Group has been engaged in litigation with streaming service Grooveshark for some time, but it may now have backup. Sony Music Entertainment and Warner Music Group have joined the latest lawsuit, according to documents filed yesterday in New York. That means the three major labels who haven’t ever licensed Grooveshark are now suing it, leaving only EMI, which inked a deal with the company after its own copyright infringement litigation in December 2009. Separately, the New York Times claims that even EMI’s partnership with Grooveshark is at risk “as the company’s relationship with Grooveshark deteriorates”. Grooveshark continues to protest: “We respect the intellectual property of all artists, and our strict policies are designed to ensure that our users only upload content to which they are entitled. This is a policy which we vigorously enforce within D.M.C.A. requirements.” Recent reports have disputed the ease with which songs can be taken down – and questioned the speed at which they then reappear on Grooveshark.