[JURIST] Attorneys for Basic Rights Oregon [advocacy website] filed a lawsuit Monday challenging the constitutionality of Measure 36 [official text], a constitutional ban on same-sex marriage approved by Oregon voters that states "It is the policy of Oregon, and its political subdivisions, that only a marriage between one man and one woman shall be valid or legally recognized as a marriage." The group claims that Measure 36 violates the fundamental principles of liberty and justice on which the Oregon Constitution [official text] is based because it restricts the role of the courts in interpreting the constitution. It also says that the measure creates multiple changes to the constitution and therefore should have been proposed as multiple amendments. The group argues voters must approve separate amendments with separate votes. Read the Basic Rights Oregon press release and more about the lawsuit [DOC]. Read the complaint [PDF]. AP has more [registration req'd].