Each political party tries to gain the upper hand by concentrating the opposition into a small number of electoral districts and then spreading its own vote across more districts in which it can achieve a comfortable win.
"And they would argue that the new legal standard is such that the IL map doesn't measure up constitutionally and they would have a pretty good argument that it should be fixed before the next round of redistricting comes along", Smith said. Four others - only Justices Ruth Bader Ginsburg and Stephen G. Breyer remain of this group - said such challenges could be heard by the court, but disagreed on the method.
The issue has torn the court for decades. Others say courts should step in.
"This case represents the first time in 31 years that a lower court struck down a district plan as an unconstitutional partisan gerrymander", the center added. Now the court has walked through that open door, with Kennedy as the likely deciding vote once again.
In this case, Registered Democratic voters asserted that Republicans used two techniques, cracking and packing, to weaken the effect of Democratic votes state wide. The ruling was the first on over 30 years that declared district lines to be unconstitutional partisan gerrymandering.
But the dozen plaintiffs - voters - said the evidence laid out in a trial in the Wisconsin case showed that "Republican legislative leaders authorized a secretive and exclusionary mapmaking process aimed at securing for their party a large advantage that would persist no matter what happened in future elections". It essentially measures and compares each party's wasted votes -those going to the victor in excess of what's needed for victory - in an election.
In most states, elected officials usually redraw the district maps once a decade for electing candidates to the state legislature and the U.S. House of Representatives. The Whitford team has proposed using a data-driven method called an "efficiency gap" to calculate whether districts are being drawn in a way that unfairly favors one party. Just 90 minutes after justices announced Monday that they would hear the case, the five more conservative justices voted to halt a lower court's order to redraw the state's legislative districts by November, in time for next year's elections. The legislature adopted new district boundaries in time for the 2012 election, when Republicans won 60 of the Wisconsin State Assembly's 99 seats, despite the fact that, in aggregate, more people voted for Democratic Assembly candidates statewide. Instead, the GOP controlled the House with a 234-201 majority. Democrats do the same, but control fewer states.