Last week, news broke that the patent-holding company Intellectual Ventures sued Motorola Mobility Holdings Inc. for patent infringement. The notorious patent troll claims that 18 Motorola products infringe on six of its patents. The suit made headlines because of the awkward position in which it places Google: While the Internet giant backs Intellectual Ventures, it also plans to purchase Motorola.

Intellectual Ventures has received flak for its patent-trolling tactics. But lately, patent litigation hasn't been so profitable for so-called trolls. According to a recent Boston University study, more than a dozen publicly listed trolls barely broke even during the past decade.

Intellectual Ventures, like other patent companies, was founded on the premise that it would finance inventors by collecting licensing fees on more than 35,000 patents. But a drop in licensing fees has spurred patent trolls to pursue infringement suits, which according to Thomson Reuters have been increasingly harder to win after a 2006 Supreme Court ruling made it more difficult to block infringers from using patents.

While Intellectual Ventures claims it has made more than $2 billion from licensing fees, its suit against Motorola, as well as other recent infringement suits against Symantec Corp., Dell Inc. and Hewlett-Packard Co. may indicate otherwise.

Read Thomson Reuters for more about patent litigation.