Gil v Whitford decision; 2018-06-18

The Supreme Court of the United States (SCOTUS) gave a 41 page document around political gerrymandering in Wisconsin. Below are my notes.

The main decision was a unanimous procedural action to bump the case back down to District Court. A concurring opinion from Kagan, Ginsburg, Breyer, and Sotomayor laid out a road may for the plantiffs to fix their case and come back and try again. I believe there is one more legal challenge not sufficiently pursued in this case.

The Procedural Rebuff

Chief Justice Roberts, et. al., primarily ruled that the plaintiffs had not sufficiently shown 'standing' for their case. They had to show that they had personally been harmed by the effects of gerrymandering. The plaintiff most cited, who must have done most of the talking during the original case, wasn't from a badly gerrymandered district. Even measuring gerrymandering is problematic and they don't like most of the measures.

The Court is aware of the mediocrity they have contributed to this situation. "Our previous attempts at an answer have left few clear landmarks for addressing the question." (p.8)

What they most wind up looking at is 'dilution of votes'. But, "To the extent the plaintiffs’ alleged harm is the dilution of their votes, that injury is district specific." (p.14) SCOTUS seems to want district by district, 'this one was packed', 'this one was cracked'. They disparage systemic, state-wide statistics, but want to focus on effects on concrete single voters.

The main decision claims that the fix could be small:
"Remedying the individual voter’s harm, therefore, does not necessarily require restructuring all of the State’s legislative districts. It requires revising only such districts as are necessary to reshape the voter’s district—so that the voter may be unpacked or uncracked, as the case may be." (p.16)
The concurring decision later suggests getting plaintiffs from every packed or cracked district, so that the result will wind up affecting pretty much all the districts.

On the "Efficiency Gap" measure:
"The difficulty for standing purposes is that these calculations are an average measure. They do not address the effect that a gerrymander has on the votes of particular citizens. Partisan-asymmetry metrics such as the efficiency gap measure something else entirely: the effect that a gerrymander has on the fortunes of political parties." (p.20)

7 of 9 members of the court felt that the case still had a chance though, so they bounced it back down to District Court. Thomas and Gorsuch wanted to just close the case and let the gerrymander stand.

The Concurring Hope

The Kagan, Ginsburg, Breyer, Sotomayor concurring opinion mostly calls out ways to make the anti-gerrymandering case better. They suggest that there's a good First Amendment claim to be made around freedom of association and the ability to effectively coordinate as a political party.
"... a plaintiff presenting such a theory would not need to show that her particular voting district was packed or cracked for standing purposes because that fact would bear no connection to her substantive claim."
"... everything about the litigation of that claim—from standing on down to remedy—would be statewide in nature." (p.2)
The main decision had a few notes, as SCOTUS frequently does, of "not our job" because they want lawmaking to be done by the legislatures and the congress, but this critique notes that,
"... only the courts can do anything to remedy the problem, because gerrymanders benefit those who control the political branches." (p.2)

They cite "Wesberry v. Sanders, 376 U. S. 1, 7 (1964)" for the "one-person, one-vote" principle and how fractionally diluting a vote is bad.

This to me sounds like an endorsement of the rising "ensemble" method of statistically challenging gerrymanders:
"In many partisan gerrymandering cases, that threshold showing will not be hard to make. Among other ways of proving packing or cracking, a plaintiff could produce an alternative map (or set of alternative maps)—comparably consistent with traditional districting principles—under which her vote would carry more weight." (p.3)

How to get a state wide effect for the state wide problem, more plaintiffs from all the packed and cracked districts:
"Assuming that is true, the plaintiffs should have a mass of packing and cracking proof, which they can now also present in district-by-district form to support their standing. In other words, a plaintiff residing in each affected district can show, through an alternative map or other evidence, that packing or cracking indeed occurred there." (p.6)
"... with enough plaintiffs joined together—attacking all the packed and cracked districts in a statewide gerrymander—those obligatory revisions could amount to a wholesale restructuring of the State’s districting plan." (p.7)

The main opinion claimed that the intent of the legislature didn't matter (documents were presented about deliberate gerrymandering) only the resulting injury to specific voters. Kagan, et.al., cite "Alabama Legislative Black Caucus v. Alabama" claiming that motive evidence counts and that statewide systemic evidence counts.

Getting back to the First Amendment free-association claim:
"The complaint in such a case is instead that the gerrymander has burdened the ability of like-minded people across the State to affiliate in a political party and carry out that organization’s activities and objects." (p.10)
"... nothing in the Court’s opinion prevents the plaintiffs on remand from pursuing an associational claim, or from satisfying the different standing requirement that theory would entail." (p.11)
The opinion closes with notes about how gerrymandering is bad and it hurts America and it has gotten a lot worse in the last two decades.

One More Thing

From the main opinion:
"The 99 members of the Assembly are chosen from single districts that must “consist of contiguous territory and be in as compact form as practicable.” §4. " (p.2)
What if the whole case is really much simpler? I can trivially show that the Wisconsin districts are not as compact as practicableThe Legislature of Wisconsin broke Wisconsin's laws. Just as in the recent Pennsylvania case, that's all you need. State court can throw out the gerrymandering.


Another Gerrymandering Game

Here's a game to practice your gerrymandering by packing and cracking. It starts pretty simple on a 3x3 board making districts of 3 blocks and builds up to a 7x7 board building 7 block districts. I am frequently a completionist on little games like this, but when you get to level 50 it will just keep going forever, so when you get there, congratulations, you won the game.


Partisan Outcome of Compact Districts

I have often been asked what the likely partisan breakdown of my maps would be. I never had the data to do that analysis, but FiveThirtyEight got the data and analyzed my maps and 7 other plans for various notions of gerrymandered and fair.
In short, my compact maps are very slightly less Republican and a bit more competitive. I've always believed that on average in the last two districtings Republicans have done more of the gerrymandering and stolen more US House seats than the Democrats have. The difference was smaller than I expected though. The difference is probably smaller than this model can usefully tell us about. All models are wrong, some models are useful, and this model is certainly not destiny but can maybe tell us something useful about the biases in the system.
FiveThirtyEight estimates that the current map has 195 safe Republican seats, 168 safe Democratic seats, and 72 competitive seats; and that this will on average elect 234.4 Republicans and 200.6 Democrats. Actually in 2016 we got 241 Republicans and 194 Democrats. 7 seats out of 435, 1.6% off, not bad.
They estimate that under my compact map that goes to 180 safe Republican seats (-15), 151 safe Democratic seats (-17), and 104 competitive seats (+32); with an expected outcome of 232.2 R and 202.8 D (D +2.2).
That 2.2 seat change looks pretty small, but I want to be optimistic about the 32 additional competitive districts. The US may be self-sorting, but while gerrymandering deliberately creates uncompetitive districts on both sides, simply not gerrymandering creates additional competitive districts. I'm not in favor of distorting districts specifically to create competitive districts (which 538 explored and created a whopping 242 competitive districts) but not deliberately creating uncompetitive districts is something I'm solidly behind. Uncompetitive districts make democracy depressing when you know you don't really have any choice, and I want this country to have more democracy.


Pennsylvania Fair District Rules

In a decision handed down on January 22, 2018 by the Pennsylvania Supreme Court, they decreed that gerrymandered districts shall be thrown out and replaced such that (emphasis mine):
any congressional districting plan shall consist of: congressional districts composed of compact and contiguous territory; as nearly equal in population as practicable; and which do not divide any county, city, incorporated town, borough, township, or ward, except where necessary to ensure equality of population. 
I stared at this paragraph for a boggled minute because the English clauses aren't clearly laid out in a prioritized order. Rationalizing it combined with what I know of redistricting law, I think the priority has to work out to be:

  1. contiguous
  2. equal population
  3. whole towns
  4. compact
If that is a complete statement of what the Pennsylvania courts want out of a district map, it's relatively simple. I clearly need to get hacking on the municipality-preserving version of my compact district solver.


Brown CS k-means Redistricting

K-Means redistricting at Brown U

I tried this 10 years ago and it's fast and simple but it isn't good enough.

The solver in the article seems to completely ignore existing boundaries including the boundaries to which the Census has actually counted data called 'blocks' (sometimes a city block, sometimes an empty square mile of Montana). If they're assuming that population is fungible and uniformly distributed within a Census block I think that's invalid. My k-means solver drew those nice straight lines but then assigned whole blocks based on whether the center of the block was one side of the line or the other. All the districts thus had ragged edges.

Because the k-means algorithm has very few data points to fiddle (district center, district weight) it can't find complex solutions. When I ran a k-means solver it couldn't find districts with close enough to equal population in a few places.

I eventually went with a solver that considered one at a time each block on a border of two districts to see if a block would be better moved to the other district. That kind of detail and flexibility made maps that weren't as ideally simple, but still had good compactness, had much better equal-population constraint satisfaction, and should be much more workable for observing the same Census blocks that existing redistricting is done on.


Sotomayor on Gerrymandering's Absurdity

"Could you tell me what the value is to democracy from political gerrymandering?
How -- how does that help our system of government?"
"... it's okay to stack the decks so that for 10 years or an indefinite period of time one party, even though it gets a minority of votes, can't get a minor -- gets a minority of votes, can get the majority of seats?"
 -- Justice Sonia Sotomayor

from oral arguments before the Supreme Court of the United States in the case of Gill v Whitford (on the matter of gerrymandering in Wisconsin)


How the SCOTUS Wisconsin Gerrymander case could go

A. Partisan gerrymander bad! Must gerrymander districts to ensure shoddy proportional representation.
B. Partisan gerrymander bad! Map must provably have no bias.
C. Meh. Whatever. Let whatever party do whatever they want.
D. BS! Puny anti-gerrymandering arguments are so bad we don’t want any courts to listen to them in 2021 either.

I feel like the plaintiffs want A. I feel like this is pretty unlikely. It would be a truly revolutionary decision that would effectively create new rules about how every state needs to redistrict. The Court is loathe to do this. Congress could pass a new 'Voting Rights Act' type law which could do this, if Congress could pass anything useful.

Option B would be the court pulling a rabbit out of a hat. I'm not sure anyone is asking for this except me.

I would mostly bet on C. No change, no big decision either way.

I am afraid of D. The court could make a ruling such that they not only throw out the Wisconsin complaint but throw out the basis and statistical means of the Wisconsin complaint thus removing the basis for future court challenges. I know a lot of people who are betting on playing a good court challenge game in 2021 to battle the expected gerrymanders which come after the next Census. There would be a lot of searching for a new strategy between now and then if SCOTUS actively disqualifies the tests being tried in the Wisconsin case.


Things are in the news now, we can read snippets of the arguments in Court, but there won't be real news until the justices make their decision in the coming months.