resident Joe Biden has signed the most sweeping gun violence bill in decades. The bipartisan compromise seemed unimaginable until a recent series of mass shootings, including the massacre of 19 students and two teachers at a Texas elementary school. The House gave final approval Friday, following Senate passage Thursday, and Biden acted just before leaving Washington for two world leader summits in Europe. The legislation will toughen background checks for the youngest gun buyers, keep firearms from more domestic violence offenders and help states put in place laws that make it easier for authorities to take weapons from people adjudged to be dangerous. Most of its $13 billion cost will help bolster mental health programs and aid schools.