In Madison v. Washington, a 5-2 decison was handed down on July 26, 2007 by Washington's Supreme Court, which stated:
"We hold that Washington's disenfranchisement scheme does not violate the privileges and immunities clause of the Washington Constitution or the equal protection clause of the United States Constitution. [...]
The privileges and immunities clause does reflect, in part, our framers' concerns with 'undue political influence exercised by those with large concentrations of wealth' and 'avoiding favoritism toward the wealthy.' Grant County II, 150 Wn.2d at 808. However, such concerns are not triggered by Washington's felon disenfranchisement scheme because it grants the 'privilege' of restoration of voting rights 'upon the same terms . . . equally . . . to all citizens.'"
July 26, 2007 Madison v. Washington (PDF 158 KB)
(Read more about this issue in our question "Should felons have to pay all fines, fees, and restitutions related to their conviction before regaining their vote?")