2010 was a wildly successful year for the Republican Party, especially in Wisconsin. Having secured the governor's office and comfy majorities in both houses of the state Legislature, the GOP can pass pretty much whatever it wants in the next legislative session. But this may only begin to tell the story of the party's gains.

The Republicans come to power just as the task of redistricting is about to begin. This will be the first time in decades that redrawing Wisconsin's congressional and legislative districts will be done entirely by one party.

Importantly, while there are rules for redistricting, there is no constitutional requirement that the boundaries be drawn in a way that is politically fair; indeed, it is hard to even define what would be fair. And disputes over whether the new districts conform to other constraints will likely be decided ultimately by the Wisconsin Supreme Court, dominated by conservatives.

It's a tremendous opportunity for the GOP, and everyone expects the Republicans to make the most of it. Here's a primer:

Why redistrict?

Districts must be redrawn every 10 years to account for the changes in population that have taken place, as measured by the U.S. Census. All congressional and legislative districts must be approximately equal in population.

For instance, the 2nd Congressional District, currently represented by Rep. Tammy Baldwin, will likely shrink in geographic size due to the rapid population growth in Dane County over the past 10 years. Parts of it will be sliced off and doled out to districts that have become less populous since 2000.

What's politics got to do with it?

Because the Legislature is given the task of drawing the districts, the process is usually hyper-partisan. In states all across the country, the party that controls the Legislature uses redistricting to maximize the number of districts that favor that party.

The U.S. Supreme Court has ruled that there is nothing unconstitutional about partisan redistricting, meaning legislatures are free to draw districts in ways that make little sense to anyone except political strategists. The only constraints, subject to judicial interpretation, are that redrawn districts must be contiguous and can't have outlandish boundaries; also, they cannot be skewed to the disadvantage of racial minorities, in violation of the federal Voting Rights Act. Just about anything else is fair game.

States including Minnesota, California and New Jersey have tried to depoliticize the process by establishing bipartisan redistricting commissions, while others have panels that submit plans to be approved by the Legislature. In Wisconsin, as in most other states, it is entirely the prerogative of lawmakers.

Ten years ago in Wisconsin, courts ended up drawing the maps because power in the Legislature was split, and the sides simply couldn't agree on a plan. With unified control of the Legislature, however, that will not be a problem this time.

How will it be done?

The key for Republicans in Wisconsin is to gain an advantage in swing districts. They do this by shifting Democratic areas of these districts into less competitive districts. In some cases that will mean packing Democratic voters into solidly blue districts (where the GOP has no hope anyway), and in other cases it will mean moving them into districts with a large enough Republican tilt that the additional Democratic voters won't present a threat.

With the help of state-of-the-art computer programs, the process is highly sophisticated and complex. Legislators are able to examine the partisan advantages of thousands of alternatives.

How does it work in practice?

No matter how committed it is to advancing its own self-interest, the party in power must recognize that there are only so many seats it can guarantee itself. The 5-3 advantage the Republican Party now has in the state's congressional delegation is probably the best it can do.

Therefore, the GOP will go to work protecting the most vulnerable of its five representatives: newly elected Reps. Sean Duffy and Reid Ribble. Although Duffy's district leans Democratic and Ribble's leans Republican, both of the northern districts are competitive. If the GOP has anything to say about it, and it surely does, that will change.

Joel Gratz, a political strategist who worked for Senate Democrats in the redistricting process in 2001, says the GOP could help Duffy by moving some of the Democratic areas of his district into that of Democratic Rep. Ron Kind, in exchange for some of the more Republican areas of Kind's current district. Similarly, some of the more Democratic areas of Ribble's district could be moved into the solidly Republican district of neighboring Rep. Tom Petri.

This process is repeated on a smaller scale to redraw state legislative districts. With a 60-38 majority in the Assembly, the GOP will be looking to protect some of its most vulnerable incumbents, including those who came to office via this fall's Republican wave.

Can anything get in the GOP's way?

The city of Milwaukee likely represents the Republicans' most significant redistricting challenge.

The Supreme Court has interpreted the Voting Rights Act as protecting areas of concentrated minority populations from "voter dilution," meaning that redistricting plans that chop up minority areas, such as inner-city Milwaukee, may be ruled a violation of the Voting Rights Act. Hence, any plan that significantly alters the heavily black district represented by Rep. Gwen Moore, or the many "majority-minority" legislative districts in Milwaukee, could be ruled illegal.

According to Ken Mayer, a UW-Madison political science professor, a Voting Rights challenge is the most likely way for Democrats to have the GOP's map disqualified.

Public opinion could be another deterrent to shameless gerrymandering. Gratz is optimistic that the increased access to the computer programs the legislators are using will mean more groups and individuals exploring the process themselves, as well as challenging the final plan.