You don't "RC." Harmony Gold did legally smack FASA around and I can prove it.
It went like this.
Back in the day, FASA was shopping around their BattleTech properties to try to get toys and/or cartoons made of them. (They eventually succeeded, but the cartoon was by all reports Teh SuXX0r.)
One of the people they showed their materials to was Playmates.
Funny thing, but later on Playmates came out with an ExoSquad line of power suits and mechs, and funny thing: one of the ExoSquad "E-Frame" mechs was nearly the spitting image of a BattleTech MadCat. (One of the newer Clans designs, completely unrelated to the Macross/Dougram material.)
Eventually, FASA noticed, said, "Hey, you can't do that!" and sued Playmates. In retrospect, this probably was not the wisest thing they could have done considering their relative sizes and budgets; it was akin to a mouse suing a tiger.
Now, as it happened, Playmates was, at the time, partnered with Harmony Gold to do some re-issues of Matchbox Robotech toys under the ExoSquad brand name. We'll probably never know whose idea it was, but it's easy to imagine someone on Playmates, or on their legal defense team, sort of tapping Harmony Gold on the shoulder and saying, "You know, those early BattleTech mech designs look awfully familiar." Based on some of their other behavior in the case, it seems like the sort of thing Playmates's rather slimy legal team would have done. (Ironically, FASA no longer made much significant use of any of those designs anyway, having long since moved on to newer stuff and completely different designs.)
It came out that FASA licensed, or thought it licensed, the mecha designs from the company that made the Macross and Dougram model kits. Maybe they thought the model company had the rights to license them. Maybe the model company thought they had the rights to license them. I'm told by people who know that Japanese contract law is severely muddled at the best of times. But it turned out that they only had the right to make models based on the shows, not sublicense the designs to other firms for other uses—and Harmony Gold, at least at the time, believed they had the rights to the Macross series, the designs used in the series, and all its derivative properties in the USA, and was willing to take action over it. (As to why they'd waited so long, well, for the late '80s and much of the '90s Harmony Gold was all but hibernating, not paying much attention to Robotech or to other Macross properties. This was probably the beginning of their wake-up process that eventually led to Robotech 3000 and Shadow Chronicles.)
So, first FASA sued Playmates, and then Harmony Gold sued FASA in response. To make a long story short, Playmates prevailed over FASA because FASA couldn't quite prove the design was similar enough, and FASA settled out of court with Harmony Gold and stopped using the Macross designs altogether. FASA eventually ceased active business operations to become an IP holding company (some game-industry vets to whom I've spoken say that the legal fees this litigation piled up were a strong contributing factor) and the BattleTech rights were later picked up by WizKids (a company founded by FASA co-founder Jordan Weisman).
All the legal documents pertaining to the case I've been able to find are linked on this page. There are a number of amusing things in them, such as a third-party representative of FASA signing a consent form that signed away rights he actually had no authority to sign away (you'd think business people would read these things before they sign, but it looks like they're just the same as the rest of us in that regard), and Playmates's lawyers trying to do an end-run around the judge when the judge refuses to pile their legal fees onto FASA (and the judge's venomous final opinion, issued on April 1st and you can't tell me that's coincidental, after it's remanded back to him to justify his decision more fully).
That should settle once and for all the idea that HG suing FASA was just an "assumption."