From the article: "The difficulty in curbing partisan gerrymandering has not been in convincing judges that the practice is unconstitutional—the Supreme Court has found that it is" where the part "the Supreme Court has found that it is" is a link that goes to this case: https://www.oyez.org/cases/1985/84-1244
That page then summarizes the Supreme Court case as follows:
Question
Did Indiana's 1981 state apportionment violate the Equal Protection Clause of the Fourteenth Amendment?
Conclusion
No. [...]
So... Am I misunderstanding something, or is the article's claim completely wrong? In which case, I'd guess that its optimism is unfounded.
I think they are trying to make the point that the specific ruling was that the state apportionment itself was fine, but that "The Court also ruled that political gerrymandering claims were properly justiciable under the Equal Protection Clause, noting that judicially manageable standards could be discerned and applied in such cases."
So I think they (not a legal scholar by any means) are saying that if the case is about gerrymandering specifically then they would be able to do something about it.
That page then summarizes the Supreme Court case as follows:
So... Am I misunderstanding something, or is the article's claim completely wrong? In which case, I'd guess that its optimism is unfounded.