Greta Gerwig, Margot Robbie, and Ryan Gosling are making a Barbie movie, which I fully expect to be both plastic and fantastic.

But while articles about the movie can't seem to resist parroting the lyrics "I'm a Barbie girl, in the Barbie world," and "Come on Barbie, let's go party," the hit song from which those lyrics are lifted -- Aqua's 1997 "Barbie Girl" -- won't be in the Barbie movie.

Why?

Trademark law and drama.

(Side note: if you're a parent, get your kids to watch "Barbie: Life in the Dreamhouse". It's one of the hidden joys of parenthood. I think it's on Netflix.)

Mattel, the company that owns "Barbie," is not exactly a fan of the song. In fact, they sued MCA Records, the company that published the song, pretty hard after it came out. And that lawsuit can teach us a thing or two about trademarks.

Trademarks are words, phrases, or symbols that identify the sources of goods or services. And so we legally protect those trademarks so consumers can reliably know who makes (or does) what goods (or services).

Mattel accused MCA of basically two breaches of trademark law: using the "Barbie" mark without Mattels's permission (infringement), and "diluting" the value of their famous Barbie mark by portraying her as a bimbo. Both of those are illegal... with some exceptions.

Some of those exceptions have to do with free speech, a Constitutional foundation here in 'Murica. Trademark rights can be used to prevent (or recover money from) confusingly similar uses of marks in the commercial marketplace, as well as some uses that diminish the value of a famous mark, and Mattel claimed that MCA did both. But trademark rights "do not entitle the owner to quash an unauthorized use of the mark by another who is communicating ideas or expressing points of view." So judges have consistently ruled that trademark protections don't entitle owners of a mark to stop artistic uses that parody their trademarked goods. And both of those are true even though MCA was making money off of the song -- the music video of which now has over a billion views on YouTube alone.

The litigation in this case got so acrimonious that MCA counterclaimed for defamation: Mattel's representatives had called referred to MCA and the incident with words like "bank robber," "heist," "crime," and "theft". The court didn't buy the claim: all of those were variations of "piracy," which of course was the claim Mattel was making, and were just "rhetorical hyperbole," which doesn't create a claim for defamation.

Judge Kozinski -- the most fun federal judge in history for about a thousand reasons -- ended the opinion in the case with:

"The parties are advised to chill."