[schoen]

The current posture of this case is a petition for certiorari (Google asking the Supreme Court to hear its appeal). These are not merits briefs (about who should win) because the Supreme Court hasn't agreed to hear it yet. They might decline to hear it and then it would go back to a lower court for further proceedings in the underlying case, but with arguably an adverse precedent out of the Federal Circuit on the books.

While I think it's now too late to file amicus briefs on the cert petition, if certiorari is granted (as Google hopes and the Solicitor General just argued against), anyone can file amicus briefs on the merits. Companies, trade associations, nonprofits, individual experts.

I don't know exactly whom people should write to in the government expressing their displeasure with the Solicitor General's position. (It's supposedly a completely nonpolitical decision, so it's unusual for people to openly lobby about it or express opinions about it to elected officials.) You can certainly write to Congress saying that you want to see legislative clarification that APIs are noncopyrightable.

[Natsu]

Slight correction regarding the part saying that 'anyone' may file one: "An amicus curiae brief may be filed only by an attorney admitted to practice before this Court as provided in Rule 5."

https://www.law.cornell.edu/rules/supct/rule_37

[schoen]

Sorry, that's quite right. I should have said "through an attorney" to avoid the possible interpretation that you could personally write and file a brief.

That rule is stricter than other Supreme Court rules related to filings by parties. If you're a natural person and not a corporation, you can file pro se pleadings before the Supreme Court in your own cases. Just not in other people's cases.

[Natsu]

Yes, that's how I interpreted it, but I thought I should point it out to avoid confusion. I also thought I remembered this being a fairly recent rules change, so there's that too.