Newswise — Takeshi Tomimori, an engineer at Japan’s Mitsubishi Electric Corp., had an idea. What if you could alert a cellphone user of incoming messages by displaying an icon on the screen? He worked out the details, and in September 2002, the U.S. Patent and Trademark Office awarded Tomimori and his employer Patent No. 6,456,841.

For nine years, the patent had a very quiet life—understandable, given that the cellphone wasn’t yet the ubiquitous gadget it is today. But think about Tomimori’s idea:

Doesn’t it sound a little like the tiny numbers that show up on an iPhone’s text, e-mail, and social media icons when there are new messages? And that may be why, in 2011, certain parties in the tech industry suddenly took an interest.

By then, the smartphone patent wars had reached a fever pitch, with companies like Apple, Google, Motorola, and Samsung engaged in globe-spanning legal battles. Against that litigious backdrop, Apple quietly acquired patent 6,456,841 from Mitsubishi. Over the next year or so, the patent changed hands several more times and became pivotal to a sweeping lawsuit brought by a patent troll against eight smartphone and tablet makers.

This case captures the intricate wheelings and dealings that go on in the headlinesand behind the scenes at major tech companies today, says tech journalist Tam Harbert. In the May 2013 issue of IEEE Spectrum, she chronicles patent 6,456,841’s circuitous path through the U.S. business and legal worlds, and the many companies, legal disputes,and business deals involved in finally settling the dispute over this simple cellphonepatent.