> On the other hand, any departure from a pure interpretation of the law is very dangerous

You should read the law in question. This would be Section 107 of the Copyright Act, which defines "fair use". It's extremely vague and is best interpreted as a set of considerations that the courts should take into account so that they can handle situations like this one on a case by case basis. If Congress wanted to be more prescriptive, they could (ETA: and if they become unhappy with the courts' decisions they still can in the future), but I think that would lead to worse outcomes.

Makes sense, and I am definitely not an expert on fair use. I'll cross out "clearly" in my aside above.

I was really just responding to the implication that SCOTUS did the right thing because "it would be a nightmare scenario" otherwise.

> courts are supposed to interpret the law

The law also states that copyright's purpose is to stimulate progress of the arts, and that's why fair use is possible. Interpreting the law also means establishing the limits of fair use.

No, fair use is possible because of the First Amendment. While it is now adopted in statute, the statute was codifying a Constitutional limit that courts previously found in copyright protection grounded in the First Amendment, not the Copyright Clause.

But, still, yes, determining the scope and applicability of fair use is part of applying the law.

Ah, I had heard of the first amendment thing but I thought it was why government work must be in the public domain (i.e. putting it under copyright would prevent reproduction and therefore infringe first amendment rights).

Good point.

If it reaches SCOTUS, it means the law is already ambiguous the way its written and that no one interpretation is obviously the correct one.

You would certainly hope so, but that logic just passes the responsibility to interpret law faithfully onto the lower courts, which are also perhaps more easily corrupted.