I'm not sure "driving force" is really accurate. The main impetus for the 1976 Act, which changed the term from 28 years with the possibility of one 28 year renewal to life + 50 was to allow the United States to join the Berne Convention. Berne required a minimum of life + 50.
The extension to life + 70, or 95 years after publication for corporate works, was in the 1998 Act. Disney did lobby for that, but the big argument for it was that was to match EU copyright terms, which went to life + 70 under the "Directive harmonising the term of protection of copyright and certain related rights" in 1993.
I think you're overestimating how much the US cares about adhering to international laws and guidelines, and underestimate the power and volume of Disney's lobbying.
Disney is pretty much only a huge force from using public domain to make money, yet they routinely do things to avoid their IP from entering the public domain.
Some examples [1]:
- Frozen (2013) from Hans Christian Anderson’s Ice Queen (1845) - Revenue = $810.3 million
- Alice in Wonderland (2010) based on Lewis Carroll’s book (1865) - Revenue = $1.02 billion
- Snow White (1937) from the Brothers Grimm folk tale (1857) - Revenue = $416 million (10th highest grossing film as adjusted for inflation)
- Aladdin (1992) from a folk tale in One Thousand and One Nights (1706) - Revenue = $504 million
Then you have their lobbying:
"In 1998, Copyright was up for it’s last copyright term extension, from life +50 years to life +70 years. Disney’s Mickey Mouse copyright had accounted for up to $8 billion in revenue in 1998 when they were lobbying for copyright extension.
Disney’s Chairman, Michael Eisener personally met with then-Senate Majority Leader Trent Lott. The day Lott signed on as co-sponsor of the bill, Disney’s PAC donated to Lott’s campaign. Within a month Disney also gave $20,000 in soft money to the National Republican Senatorial Committee. Of the 13 initial sponsors of the House bill, 10 received contributions from Disney’s PAC. On the Senate side, 8 of the 12 sponsors received contributions" [2]
Protect $8B with some cheap lobbying. What a deal!
Seriously the value from lobbying is outrageous from a business standpoint. Even if the bribes were 100x what they are now it'd be worth it. Screaming deal for companies working against public interests, as it has been for decades.
Honest question: How are those examples different from studios adapting, say, Shakespeare to a more "modern" context? 10 Things I hate About You (1999) is an adaptation of Taming of The Shrew.
The difference is that those studios don't try to rewrite laws via lobbying to block their IP from entering the public domain after profiting greatly off public domain.
If I'm understanding copyright law correctly (I am not a lawyer, but am familiar), Disney has copyrighted the specific adaptation of those stories from the public domain - not the stories themselves. So someone can't, say, do Snow White in the same way as Disney did (same script, artistic style etc) but they can do things like Snow White and The Huntsman (2012), which made ~$397m worldwide. I do agree that rewriting laws via lobbying is a problem. I'm just not sure that Mickey Mouse should be public, seeing as how that IP is so tied up in so much of what constitutes value for Disney.
Edit: Just read a bunch about the history of Disney and the Mickey IP. Yeah, totally not comfortable with that.
https://en.wikipedia.org/wiki/Copyright_Term_Extension_Act