Here’s an interesting piece that argues that there are four potential constitutional arguments that could be made:
https://scholarship.law.cornell.edu/cgi/viewcontent.cgi?article=1084&context=cjlpp
That's an interesting law review article. I read it a couple of times. Thanks for linking it. As is the case with many law review comments, there is a high level of surplusage mumbo jumbo included. None of the four arguments, equal protection, first amendment, competitiveness, or legislating with impartiality, in my view touch on any constitutional requirement or constitutional prohibition. While interesting reading, none of the four arguments state a justiciable claim that courts can or should address.
While I agree that excessive partisanship in drawing boundaries is inconsistent with democratic principles, I fail to see how drawing boundaries should be different from excessive partisanship in any legislative action such as passing health care, a budget, or tax policy. The essential point of a representative democracy is the process of legislation, meaning a lot of debate, negotiation, and compromise. Any policy that is thwarted or imposed by the refusal to debate, negotiate, or compromise is in a large sense undemocratic. Yet the courts will never declare a law unconstitutional because one side in a legislature had its way. I see districting as the same.
I revisited the Colorado redistricting law. The law before the 2018 change included these factors in judicial review of redistricting:
(1) In determining whether one or more of the congressional districts established in accordance with
section 44 of article V of the state constitution are lawful and in adopting or enforcing any change to any such district, courts:
(a) Shall utilize the following factors:
(I) A good faith effort to achieve precise mathematical population equality between districts, justifying each variance, no matter how small, as required by the constitution of the United States. Each district shall consist of contiguous whole general election precincts. Districts shall not overlap.
(II) Compliance with the federal “Voting Rights Act of 1965”, in particular
42 U.S.C. sec. 1973;1 and
(b) May, without weight to any factor, utilize factors including but not limited to:
(I) The preservation of political subdivisions such as counties, cities, and towns. When county, city, or town boundaries are changed, adjustments, if any, in districts shall be as prescribed by law.
(II) The preservation of communities of interest, including ethnic, cultural, economic, trade area, geographic, and demographic factors;
(III) The compactness of each congressional district; and
(IV) The minimization of disruption of prior district lines.
The 2018 change is:
(2)(a) As much as is reasonably possible, the commission's plan must preserve whole communities of interest and whole political subdivisions, such as counties, cities, and towns.
(b) Districts must be as compact as is reasonably possible.
(3)(a) Thereafter, the commission shall, to the extent possible, maximize the number of politically competitive districts.
In the former, political competitiveness is not mentioned at all, in the latter, competitiveness is clearly subordinated to other factors.
In sum, I don't think excessive partisanship should ever be a reason for a court to void a legislative act. The fact that the "excessive partisanship" is part of the legal analysis shows we are talking about a legislative function, not a judicial function. In any event, the voters and their representatives have plenary control over the amount, and role, of political partisanship in drafting legislation.
