What happens if the Virginia General Assembly and Gov. Bob McDonnell (R) cannot agree on a new map for the state legislature and redistricting ends up in the courts?

Is a judge likely to show deference to state lawmakers and enact the plan approved by the state Senate and House of Delegates that was vetoed by McDonnell? That’s what Sen. Dick Saslaw (D-Fairfax) has contended.

Is a judge more likely to pick up plans drawn up by McDonnell’s independent advisory commission, since the commission drew those maps free from partisan considerations?

The answer: It’s totally unpredictable.

That’s according to Columbia Law School Professor Nathaniel Persily, who has served as the court-appointed redistricting expert in three legal proceedings in other states.

“Courts adopt very different processes and come out with very different results,” Persily said. “One can look at all the redistricting cases across the country and see more differences than similarities.”

Persily, who has written one of the only academic works describing how court redistricting works (a 2005 article in the George Washington Law Review), said the case will land in court when a citizen files suit, arguing that it looks like the legislature is deadlocked and new plans are not likely to be drawn up in time for the November election.

The resident would argue that without new plans, the elections would have to be held using maps drawn up 10 years ago.

New census data, the citizen would argue, shows the districts included in those maps are now unconstitutional because they no longer have about the same number of people in them--thus, violating the constitution’s guarantee that everyone’s vote counts the same.

That case could be filed in either a state court or a federal court, Persily said. Sometimes, suits are filed in courts at both levels, as plantiffs seek a legal forum most likely to ultimately draw maps to their liking.

Once in the court, he said, judges have no established rules for how to proceed. Some hold public hearings, much like legislative bodies that conduct redistricting every 10 years in response to the census.

Some ask parties to the suit to propose maps and then choose among them. Some appoint a special master and ask that person to draw new maps. Some appoint their own legal expert--a person like Persily--and draw maps themselves with their expert’s help.

In cases where judges draw new maps, there are also no hard and fast rules about what guiding principles they follow.

Sometimes they try to adopt maps that change current district lines as little as possible. Sometimes they announce at the outset that they plan to take incumbency into account, and sometimes they announce they plan to ignore incumbency.

The same goes for whether they plan to respect the legislature’s current partisan breakdown or whether they plan to aim for competitive elections.

“The courts are inconsistent about these things,” Persily said.

Regardless, judges are always unhappy to have to pick legislative winners and losers and always hopeful the legal process will compel politicians to solve their own issues.

Persily recalled one case he worked on in New York, when the state legislature could not agree on new congressional districts following the 2000 census. The judge asked Persily to draw up a new map that largely mirrored a Republican proposal for Long Island, a Democratic proposal for New York City and then drew entirely new districts for the competitive upstate region.

Elected officials in both parties hated the judge’s map. The result? A sudden charge of heart that broke the logjam that had prevented them from coming up with their own plan.