MADISON, Wis. — Saying President Obama has violated his constitutional duty and has exceeded his administrative power, Gov. Scott Walker joined governors and attorneys general in 17 states Wednesday in a lawsuit seeking to block Obama’s executive order on immigration. “The immigration system is broken, but this is an issue that should be addressed through collaborative federal action, not unilateral action by the President,” Walker said in a statement, after the complaint was filed in U.S. District Court in Brownsville, Texas. “President Obama’s actions represent a violation of his constitutional duty to faithfully execute the laws and exceed the limits...