Supporters of legislative redistricting reform in Illinois were heartened Monday by a decision by the U.S. Supreme Court to consider whether Wisconsin politicians went to too far in redrawing state electoral maps to their partisan advantage.

Many critics of Illinois politics believe the extreme political gerrymandering that Wisconsin Republicans are accused of employing to solidify power is analogous to the vaunted remapping efforts that have allowed Illinois Democrats and House Speaker Mike Madigan to maintain control.

Funny thing about that.

By the standard the U.S. Supreme Court is being asked to adopt in the Wisconsin case, Illinois Democrats are pikers when it comes to gerrymandering.

OPINION

The Wisconsin case revolves around whether a redistricting plan pushed through by the state’s Republican leadership in 2011 violated Constitutional protections.

The GOP plan packed Democratic voters into the fewest districts possible or spread them out, both maneuvers intended to dilute their influence. This helped Wisconsin Republicans gain a stranglehold over the state Assembly.

Such partisan gamesmanship has been going on for centuries throughout the country, including Illinois, and while the Supreme Court has taken a dim view of the practice, it has always stopped short of setting a standard for how much gerrymandering is too much.

But Justice Anthony M. Kennedy held out the possibility in a 2004 ruling that such a standard could be found, prompting lawyers in the Wisconsin case to offer what they call the “efficiency gap.”

The efficiency gap, developed in part by University of Chicago law professor Nicholas Stephanopoulos, purports to measure the number of “wasted” votes in a given legislative district.

I honestly have a little trouble following it, but they say a vote is wasted if it is cast either “for a losing candidate” or “for a winning candidate but in excess of what she needed to prevail.” Then they divide that number by the total votes cast to produce a percentage, which they call the efficiency gap.

If a map is drawn legitimately, it would theoretically waste about the same number of Democrats and Republicans, yielding an efficiency gap of zero.

Stephanopoulos and co-author Eric McGhee say a legislative map with an efficiency gap of 8 percent or more should be regarded as extreme political gerrymandering. Wisconsin’s gap was 13.3 percent in 2012.

Illinois’ Democratic-drawn maps are not in that league.

“In a nutshell, Illinois’ plans have had quite small efficiency gaps this cycle at both the Congressional and the statehouse level,” Stephanopoulos told me by email Monday.

“I don’t doubt that the maps were drawn with partisan intent, but that intent hasn’t manifested itself in anything like the efficiency gaps we saw in Wisconsin,” he continued.

Stephanopoulos said he couldn’t share specific figures for Illinois while the Wisconsin case is in court.

But he said, “They’re all below 5 percent for Illinois, and they average out to very close to zero.”

Let me hasten to interject that there is absolutely no doubt that Illinois Democrats drew legislative maps to their own advantage in 2011, just as they do every 10 years when they get the chance, just as the Republicans do when they have an opportunity.

What’s interesting is that Madigan et al apparently did so more carefully than some have appreciated.

Last year, the Illinois Supreme Court blocked the latest citizen initiative attempting to put a referendum before state voters that would permit them to change the Constitution to allow a bipartisan commission to perform redistricting instead of the Legislature.

CHANGE Illinois, which has picked up that organizing effort, welcomed Monday’s news.

“Now that the U.S. Supreme Court has taken on the landmark partisan gerrymandering case in Wisconsin, the highest court in America could establish clear constitutional limits on partisan map drawing that could have applicability to Illinois and other states,” said Brad McMillan, the group’s vice chair.

If nothing else, a Supreme Court ruling might prevent the party in power in Illinois from going whole hog after 2020.