Most Relevant Cases on the Constitutionality of Open Primaries

The Connecticut case Tashjian v. Republican Party of Connecticut:
      http://caselaw.lp.findlaw.com/scripts/getcase.pl?court=US&vol=479&invol=208

The California case is California Democratic Party et al v. Jones:
      http://supct.law.cornell.edu/supct/html/99-401.ZS.html

The Oklahoma case is Clingman v. Beaver et al:
      http://supct.law.cornell.edu/supct/search/display.html?terms=clingman%20v%20beaver&url=/supct/html/04-37.ZS.html

The Virginia case is Miller v. Brown (not yet before SC, but closest to Idaho’s situation):
      http://pacer.ca4.uscourts.gov/opinion.pdf/052254.P.pdf