Twin Falls County v. Idaho Commission on Redistricting, 271 P.3d 1202

Idaho Supreme Court invalidates Plan L87 for violating Art. III, §5 by dividing too many counties.
The six-person reapportionment commission adopted Plan L87 (Sept–Oct 2011) after a prior failed attempt by a different commission.
Petitioners challenge Plan L87 as unconstitutional; Respondents defend plan under constitutional and statutory framework.
Court applies a hierarchy: federal Equal Protection controls population deviation; Idaho Constitution Article III, §5 restricts county divisions; I.C. §72-1506 provisions guide the process.
Majority holds Plan L87 divides twelve counties, exceeding the minimum necessary to comply with the U.S. Constitution, thus invalid.
Court directs the commission to reconvene and adopt a revised plan that complies with both state and federal requirements.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Does Plan L87 violate Art. III, §5?	Plan L87 splits too many counties.	Plan L87 necessary to meet federal equal protection.	Yes, invalid under Art. III, §5.
What is the proper remedy and process after violation found?	Courts should immediately halt Plan L87.	Remedy lies in reconvening to adopt a compliant plan.	Plan L87 must be revised; reconvene ordered.

Reynolds v. Sims, 377 U.S. 533 (U.S. 1964) (required population-based apportionment; 10% deviation presumption)
Brown v. Thomson, 462 U.S. 835 (U.S. 1983) (deference to state decisions; substantial discretion in apportionment)
Hearne v. Smylie, 225 F.Supp. 645 (D. Idaho 1964) (federal constitutional relevance to Idaho apportionment)
Bonneville County v. Ysursa, 142 Idaho 464 (Idaho 2005) (discussed mechanism for county-splitting and deference to Commission)
Bingham County v. Comm'n for Reapportionment, 137 Idaho 870 (Idaho 2002) (analysis of one-person, one-vote and county-splitting factors)
Hellar v. Cenarrusa (Hellar III), Idaho 106 Idaho 586 (Idaho 1984) (courts defer to legislative/apportionment discretion within constitutional bounds)