Idaho Secretary of State Ben Ysursa is in federal court today, defending the state's primary election system in a lawsuit from his own party, the Idaho Republican Party. The party sued to try to force the closure of its primary elections to anyone other than registered Republicans; Idaho has never had party registration. The three-day bench trial before U.S. District Judge Lynn Winmill kicked off this morning with cross-examination of expert witnesses, as much of the arguments and direct examination of experts has been submitted in advance in writing. First up today was Bob Moore, of Moore Information, which conducted a survey the party cites to argue that "crossover" voting by Democrats in Republican primaries violates its rights and has forced Republican candidates to modify their positions.

The state, in its trial brief, argues that evidence, including expert reports submitted by both sides, shows "no legally significant adverse impact to the Republican Party from operation of Idaho's long-standing primary system.  The party instead has thrived electorally and achieved a level of political dominance unmatched in any other state."

After the party sued, both sides filed motions for summary judgment in the case in 2008; the court denied both in 2009, and asked for proof about whether crossover voting happens in Idaho, and to what extent it affects the message of the Idaho Republican Party and its candidates. In this week's trial, the two sides are sorting through what each has submitted as proof. You can read the party's trial brief here and the state's trial brief here.