The Supreme Court heard arguments Monday in a potentially landmark immigration case, United States v. Texas. At the heart of the case are two executive orders issued a year and a half ago by President Obama, whose administration is being sued by Texas and 25 other states to stop them from taking effect. They won in lower courts and now the justices are deciding the issue. Their decision could affect the lives of 4 million undocumented immigrants, many who came to the U.S. as children, others are the parents of American citizens.