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Cisco intellectual property lawyer Rick Frenkel is a case study in how not to mix your personal blog with your day job. Frenkel wrote the anonymous Patent Troll Tracker blog about "those thought to opportunistically act against alleged patent infringements," reports Forbes. Eventually, Frenkel blogged about a case in which Cisco was the defendant. Guess what happened?

The blog suggested that attorneys for the plaintiff, ESN, which holds a telecom patent, persuaded a courthouse clerk to switch the suit's filing date to a more favorable one.

Days after Frenkel's unmasking, ESN Texas attorneys T. John Ward Jr. and Eric Albritton filed separate defamation actions in state court against Cisco and Frenkel. Ground for suing Cisco? When Frenkel unveiled his identity, he wrote that his "direct manager" knew about his blogging.

That may not be enough to immunize Cisco from any potential liability.

(Still from Fora.tv)