Kim Soffen in the NYT:
Buoyed by a Supreme Court ruling, opponents of gerrymandering want to get more state legislatures out of the business of drawing congressional districts. So it’s worth examining the performance of the independent redistricting commissions validated by the court on Monday.
Arizona, via a ballot initiative in 2000, was one of the first states to entrust congressional boundaries to an independent commission, and California followed suit in 2010. Four other states have their congressional districts drawn by independent panels in an effort to make the process less partisan and yield more competitive districts. But those commissions were formed by their respective state legislatures and were not affected by Monday’s ruling.
Measuring the success of an independent commission is tricky, as it’s impossible to know how a legislature’s lines will have differed from a commission’s in the same year. And other factors like people’s relocations can alter a district’s ideological balance. But the evidence suggests that the commissions yielded more competitive races in Arizona and California.
The Arizona ballot initiative, Proposition 106, directed the commission to make the districts competitive “where to do so would create no significant detriment to the other goals.” Those goals included complying with theVoting Rights Act, equality of population, compactness, contiguity and respect for communities of interest and natural boundaries.
The “no significant detriment” clause, according to Willie Desmond, the lead map drawing consultant hired by the Arizona commission for the 2011 redistricting, “was kind of hard to interpret.” He said in an interview, “The commissioners all viewed that in slightly different ways depending on whether they wanted there to be more competitive districts.”
Even so, the maps resulting from both the 2001 and 2011 redistricting in Arizona were among the most competitive in the nation, as measured by election results. They had an average margin of victory more than 28 percent lower than that of the United States as a whole. Indeed, two of its nine districts were among the 29 in the nation that had margins of victory under 5 percent in 2014.
More here.