major funding for the pbs newshour has been provided by: >> bnsf railway. >> the william and flora hewlett foundation, working to solve social and environmental problems at home and around the world. and with the ongoing support of these institutions and foundations. and... this program was made possible by the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank you. >> woodruff: a massacre in the middle of the night, afghan civilians slaughtered as they slept, an american soldier the lone suspect. u.s. officials struggled to make sense of those stark facts today, as afghans demanded justice. ray suarez begins our coverage. >> suarez: afghan soldiers were on alert in canned half today, stepping up security to prevent revenge attacks. anti-american rage was boiling after a u.s. soldier allegedly shot and killed 16 afghans in their homes, nine of them children. >> they killed a child. he was two years old. was this child the taliban? believe me i have not seen a two-year-old taliban yet. >> suarez: afghan officials said the soldier left

bnsf, the engine that connects us. >> and by the alfred p. sloan foundation. supporting science, technology, and improved economic performance and financial literacy in the 21st century. and with the ongoing support of these institutions and foundations. and... this program was made possible by the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank you. captioning sponsored by macneil/lehrer productions captioned by media access group at wgbh access.wgbh.org

bnsf, the engine that connects us. and by the alfred p. sloan foundation. supporting science, technology, and improved economic performance and financial literacy in the 21st century. and with the ongoing support of these institutions and foundations. and... this program was made possible by the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank you. >> brown: the president's health care overhaul was back before the u.s. supreme court for a second day, and the justices zeroed in on the central issue. newshour health correspondent betty ann bowser begins our coverage. >> reporter: the arguments today inside the court went to the heart of the affordable care act. whether it's constitutional for the government to require its citizens to purchase health insurance. it's by far the most unpopular and contentious part of the new law. although the term "individual mandate" does not appear in it. the mandate requires that practically all americans have health insurance. that can be through medicare, medicaid or

bnsf, the engine that connects us. >> and by the alfred p. sloan foundation. supporting science, technology, and improved economic performance and financial literacy in the 21st century. and with the ongoing support of these institutions and foundations. and... this program was made possible by the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank you. captioning sponsored by macneil/lehrer productions captioned by media access group at wgbh access.wgbh.org america." >> funding for this presentation is made possible by -- the freeman foundation of new york, stowe, vermont, and honolulu, newman's own foundation, and union bank. >> at union bank, our relationship managers use their expertise in global finance to guide you through the business strategies and opportunities of international commerce. we put our extended global network to work for a wide range of companies, from small businesses to major corporations. what can we do for you? what can we do for you?

major funding for the pbs newshour has been provided by: >> bnsf railway. >. the william and flora hewlett foundation, working to solve social and environmental problems at home and around the world. and with the ongoing support of these institutions and foundations. and... this program was made possible by the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank you. >> woodruff: the u.s. supreme court opened three days of arguments today on the nation's health care reform law. newshour health correspondent betty ann bowser begins our coverage. >> reporter: supporter and opponents of the affordable care act took to the streets early this morning to make their case to the cameras outside of the court. it was a far cry from the subdued atmosphere that would unfold later in the day inside. >> why do you want to argue? >> reporter: emotions have run high since congress passed the law two years ago. in fact almost by entirely by democrats and president obama. >> what do we want? >> reporter: one of its primary

bnsf, the engine that connects us. >> and by the bill and melinda gates foundation.idea that all people deserve the chance to live a healthy, productive life. >> and with the ongoing support of these institutions and foundations. and... >> this program was made possible by the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank u. captioning sponsored by macneil/lehrer productions captioned by media access group at wgbh access.wgbh.org

major funding for the pbs newshour has been provided by: bnsf railway. >> and by the alfred p. sloan foundation. supporting science, technology, and improved economic performance and financial literacy in the 21st century. >> and with the ongoing support of these institutions and foundations. and... this program was made possible by the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank you. >> woodruff: the president of afghanistan voiced new outrage today over the killings of 16 civilians in his country. hamid karzai made angry new accusations against the u.s., as the american suspect in the shootings was being flown home. karzai fired off his new broadside after meeting with relatives of those murdered last sunday. >> it is by all means the end of the rope here, the end of the rope. this form of activity, this behavior cannot be tolerated. it is past, past, past the time. >> woodruff: the killings took 16 lives-- mostly women and children, shot as they slept, in two separate villages. karzai demanded the u.s. military b

bnsf, the engine that connects us. and by the alfred p. sloan foundation.porting science, technology, and improved economic performance and financial literacy in the 21st century. and with the ongoing support of these institutions and foundations. and... this program was made possible by the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank you. >> woodruff: super tuesday came and went and the republican presidential race carried on today with no end in sight. instead, the most of the candidates returned to campaigning across the country. in winning six states, mitt romney still failed to deliver a knockout blow last night. but today, he insisted it will come. >> i am prepared to fight all the way to become the nominee. and, you know, i was pleased with our success last night. >> woodruff: on cnbc, the republican front-runner insisted he knows the path that will take him to victory. >> obviously, we've got a very and we've got the time and resources and a plan to get all the delegates. we think that w

bnsf, the engine that connects us. >> and by the alfred p. sloan foundation. supporting science, technology, and improved economic performance and financial literacy in the 21st century. and with the ongoing support of these institutions and foundations. and... this program was made possible by the corporation for public broadcasting. and by coribuons your pbs station froviewers li you thank you. >> suarez: new violence erupted in afghanistan today after a u.s. soldier allegedly killed 16 civilians on sunday. at the same time, president obama condemned the killings again in his strongest words yet. and the u.s. military found probable cause to continue holding the suspect soldier. >> reporter: gun fire exploded again this morni at the scene of sunday's massacre near kandahar. insurgents opened fire on a visiting delegation of senior afghan officials who had come to pay respects, including two of president hamid karzai's brothers. they were unhurt, but one afghan guard was killed and another wounded. the taliban said it was in retaliation for the killing of 16