Apple’s lawsuit against HTC comes well into the Internet age, after a 10-year run of “troll” lawsuits has transformed the patent litigation landscape to the point that such suits now make up the bulk of many Silicon Valley litigators’ practice.

It’s fairly unusual in the modern era for a market leader to initiate a patent suit. Which is not to say large operating companies don’t sue for patent infringement. They do. But on the relatively rare occasions when they do launch such litigation, it tends to fall into a couple of categories.

First, there are big companies with established licensing programs (IBM, Honeywell) that sometimes sue companies they don’t directly compete with as a way of extracting licensing revenue. Second, big companies with slightly more Industrial Age roots sometimes sue in a bid to win some tribute from the new breed of technology companies (see, for example, Kodak’s patent claims against Samsung, LG, Apple, and RIM over cell-phone cameras or Xerox’s lawsuit against Google and Yahoo over search engine technology). Finally, there are a handful of suits in which a large patent-holder goes after a true rival in the hopes of protecting a deteriorating market share (see Nokia v. Apple).

The indirect targets of Apple’s lawsuit, of course, are Google and its Android operating system. Still, the suit doesn’t fit cleanly into any of the above categories, because right now Apple, along with Blackberry maker Research in Motion, is top dog in the smartphone market. But the company may be getting nervous about the long-term security of its position–or it may just be interested in using patents to to make life difficult for its competitors.

via Patent Litigation Weekly: Digging Beneath the Surface of Apple v. HTC.