Shannon Appelcline (Designers & Dragons) talks about it here! With infographics!
"Every company interacts with the rest of the industry in a different way. For Chaosium it's been more than 40 years of licensing, while Target Games created and defined roleplaying in its home country of Sweden. Dave Nalle's Ragnarok Enterprises instead influenced designers and publishers through interactions in A&Eand Abyss. As for TSR, the founder of our industry: as wags have put it: they sue regularly."
They also sued WotC once!
"Every company interacts with the rest of the industry in a different way. For Chaosium it's been more than 40 years of licensing, while Target Games created and defined roleplaying in its home country of Sweden. Dave Nalle's Ragnarok Enterprises instead influenced designers and publishers through interactions in A&Eand Abyss. As for TSR, the founder of our industry: as wags have put it: they sue regularly."
They also sued WotC once!