In the Wisconsin gerrymandering case, Rebecca Clarke v. Wisconsin Election Commission, the Wisconsin Supreme Court ruled that the current map of state assembly and state senate district boundaries violates the constitution because it contains a large number of districts that are not "contiguous."  That is, some districts contain parts disconnected from other parts.      

         Although contiguity was the key constitutional issue, the additional motivation for the lawsuit was to change those legislative district boundaries that systematically lead to   non-representative government: the ratio of legislative seats held by the different political parties is wildly out of proportion to the ratio of voter preferences for candidates from those parties.   Over the past four election cycles, for example, the voters expressed a preference for Democrats by over 50%,  but Democratic party candidates held a mere 36% of the Assembly seats, and had no chance of gaining a majority of seats in the state legislature.  Ideally, the district boundaries of the 99 assembly seats  and the 33 state senate seats would be neutral, i.e.,  directly reflecting the statewide party make-up of the voting electorate.  With neutral district boundaries, elections would be determined by  candidate  quality, voter policy preferences, and the energy and commitment of the supporters.     

 Now for the Hard Part:  Choosing the Map

            The court offered the parties to the lawsuit  the opportunity to submit remedial  maps that cure the contiguity  problem.    The court will sift through submitted maps while bearing in mind this key sentence that appears within the majority opinion:    "We do not have free license to enact maps that privilege one political party over another."     Accordingly,  the task is to choose the map with minimum -- ideally zero -- "privilege" of one political party over another.  

Outside Expertise and Technical Requirements

          For technical assistance, the court has appointed two experienced consultants:  Dr. Bernard Grofman of the University of California at Irvine, and Dr. Jonathan Cervas of Carnegie-Mellon University.     They list seven technical requirements for map proposals:  districts must have  nearly equal population; have minimal splitting of existing political subdivisions, such as county and city lines;   display complete contiguity; have acceptable compactness;  comply with federal law of equal protection and voting rights;  consider communities of interest; and address political neutrality. 

         The consultants  require that proposed maps be submitted to DavesRedistricting.org, a website established to add transparency to the redistricting process.   DavesRedistricting.org  provides a place to compare maps both visually and with numerical scores for each of the criteria listed by the consultants.      

 Demystifying Modern Map-making

          The high-tech methodology being used by the mapmakers and the consultants can be puzzling. That puzzlement can be alleviated somewhat by reading the Amicus Brief submitted on November 8, 2023 by Professor Matthew Petering of the UW-Milwaukee College of Engineering. In that brief, Petering described a complex computer algorithm he designed to create a map that optimizes the seven criteria.  

         Because Petering  is not a party to the lawsuit, his maps are not being considered by the court or its consultants. Nonetheless,  he submitted a map to DavesReedistricting.org so it could be scored and displayed alongside  the six maps submitted by the parties.  In turn, Urban Milwaukee's Bruce Thompson has  greatly simplified the job of comparing the seven maps by reducing the numerical scores to colored bar charts.  

Data

         As Dr. Petering explains, his  algorithms must be programmed    using voting data from recent statewide elections in Wisconsin, i.e., data not affected by the gerrymandering.  Petering has also shown that because Democratic voters are more clustered in urbanized areas than the more widely-dispersed Republican voters, the algorithms must use ward-level election data from recent statewide elections to get a fair map. be programmed with data on  voter residential patterns.  (Of course, data on individual voters is not used and is not available.)   This use of data is in agreement with the opinions expressed by Judge Adelman and Fred Kessler, two learned scholars of the problems of map making (see Further Readings below). 

          To illustrate numerically the importance of using ward-level data, Petering provides maps with and without using that data from recent statewide elections.  To compare the results,  he plugged both maps into the DavesRedistricting.org scoring system.  With that data, the DavesRedistricting.org estimates that Petering’s map provides Democrats with 51 seats in the Assembly, proportional to their statewide share of votes.  Without the data, that drops well below their proportional share to about 43  seats with a very low likelihood of a legislative majority, a result that locks in the partisan privilege the Republicans have enjoyed.  In other words, the use of election data to make maps does not introduce partisan bias; it is the failure to use that  data that results in partisan bias. 

 "Natural Gerrymandering" Debunked

         It is a statistical fact that Dem voters live in a more concentrated residential pattern than Republican voters.  This has led to a plausible but wrong notion called  "Natural Gerrymandering"  i.e.,  because of the greater concentration of Democrats, partisan privilege cannot be eliminated.    If true, this hypothesis implies that Democratic Party  policies and proposals will forever be in the minority. Dr. Petering has debunked this defeatist notion in the best way possible: counter example. He produced a map with proportional representation, the equivalent of zero partisan privilege.  As the bar graphs in Bruce Thompson's article so vividly show,  Petering's map is better on minimizing partisan privilege than any  map under consideration by the court.  His maps earn especially strong scores of 99 and 100 (100 is best) for proportionality in the Assembly and Senate, respectively,   indicating  virtually no privilege FOR EITHER PARTY.  Although for  procedural reasons his map cannot be included among those considered by the court, Petering's achievement shows that  neither the Court nor its consultants should accept incomplete solutions of the partisan privilege problem.

Further reading   

 "Political Fairness in Redistricting: What Wisconsin’s Experience Teaches," The University of Memphis Law Review, Vol 49, 2019, Judge Lynn Adelman

 "How to Draw Fair Maps in Wisconsin," Capitol Times, Nov 14, 2020. Fred Kessler, former legislator and re-districting expert.

"Ranking the 7 Proposed Legislative  Maps" by Bruce Thompson, Urban Milwaukee, Jan 17,  2024.

District Solutions LLC  www.districtsolutions.net, Amicus Briefs of Matthew  Petering, Clerk of Wisconsin Supreme Court 11-08-23 and 01-22-24.