Joshua A. Douglas is a law professor at the University of Kentucky College of Law who specializes in election law, voting rights, and constitutional law. He is the co-editor of " Election Law Stories ." Follow him on Twitter @JoshuaADouglas . The opinions expressed are his own. This commentary has been updated from an earlier version.

(CNN) Voters should select their representatives, not the other way around.

On Tuesday morning, the Supreme Court will consider the limits of partisan gerrymandering, where politicians essentially choose their constituents by manipulating the electoral maps. The case, from Wisconsin , could become the biggest and most significant election law case in years and will affect elections across the country for decades to come.

This case revolves around redistricting -- specifically, district lines in Wisconsin that challengers contend the Republicans unconstitutionally drew to favor themselves. The court will face a stark choice: allow politicians to continue rigging the rules of the game to their own advantage, harming voters in the process, or allow courts to police and correct the worst partisan power grabs from the redistricting process. It is high time for the high court to stop politicians from drawing district lines for their own political benefit.

All eyes will be on Justice Anthony Kennedy. As the likely swing vote in this case, he should recognize that partisan gerrymandering has run rampant and that the courts can stop the worst abuses. We will remember Justice Kennedy's legacy on the court in part based on how he rules in this case.

More broadly, the court should rule that pure political motivations for election rules are unfair and unlawful. It must scrutinize carefully any election law passed primarily to benefit the party in power. Voter ID laws, campaign finance rules, and redistricting maps are all suspect when the primary motivation for them is to stay in power.

The stakes could not be higher for this fundamental question now facing the Court. As it now stands, the groups who control the map-drawing process can help to sustain their dominance and engineer the political agenda.

Do we want a democracy in which politicians (of any party) can virtually assure their re-election and continued dominance in a state simply because of the way that they draw the maps? Or does a strong democracy require meaningful checks on partisan abuses in election rules?

The answer should be easy: the Constitution exists to prevent the very kind of political entrenchment that partisan gerrymandering represents.

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A recent study from the Brennan Center found that gerrymandering has resulted in 16 or 17 additional Republican seats in Congress, or about two-thirds of the 24 seats Democrats would need to take over the House. Similarly, some point to partisan redistricting after the 2010 census as the main reason Republicans retained the House in 2012. The practice is also rampant in state legislatures across the country. Both Democrats and Republicans do it.

Because of a series of Supreme Court cases, especially one from Pennsylvania in 2004 , courts have been impotent to stop this practice thus far. In that 2004 case , the justices split in their findings: four justices ruled that claims of partisan gerrymandering are purely "political questions" that the federal courts should not entertain; four justices offered different standards to measure the worst abuses in partisan gerrymandering; and Justice Anthony Kennedy, in the middle, said that he could not agree with any of the offered tests but would leave the door open for a future standard to emerge.

The result was that a majority could not agree on a test to measure partisan gerrymandering, and without any meaningful checks the practice flourished.

Enter the Wisconsin case. The plaintiffs, complaining about an egregious Republican gerrymander of the state legislature, have come up with a new test to measure when politics has over-infiltrated the redistricting process.

Called the " efficiency gap ," the standard looks at the number of "wasted votes" -- those not contributing to a winning candidate's election -- for each political party in a statewide map. In essence, the standard, created by a law professor and a political science professor , provides a numerical way to test the partisan disadvantage in a redistricting plan.

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An unconstitutional partisan gerrymander , according to the plaintiffs, is one that maximizes the wasted votes for the minority party while minimizing them for the majority party that drew the map (it includes both lost votes cast for the candidates who lose and surplus votes cast for winning candidates).

Late last year a lower federal court, splitting 2-1, adopted a modified form of this efficiency gap test and struck down Wisconsin's map. This ruling represented the first time in over three decades that a federal court had declared a map to be an unconstitutional partisan gerrymander. The Supreme Court will now consider that decision.

If the court agrees with the plaintiffs and the lower court, then there will finally be a meaningful way to fight back against the worst abuses in partisan gerrymandering. Adopting a test for courts to strike down partisan gerrymanders would go a long way to ensuring that fair elections, not unfair election rules, decide who wins.

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Yet if the court reverses the Wisconsin panel's decision and once again rules that there are no judicial tests available to stop partisan gerrymandering, then we can expect ever more egregiously partisan redistricting.

A ruling rejecting this standard will send a signal to politicians of all parties that there are virtually no limits to them drawing maps simply in an effort to stay in power.

Election rules should be impartial. They should allow policy and ideas -- not the rules of the election itself -- to win out in a political campaign. The court's decision in this case will determine whether that ideal becomes a reality.