The line to watch Tuesday's oral arguments for and against gay marriage started forming outside the Supreme Court on Friday. The justices will decide two main issues: Should states be required to issue marriage licenses to same-sex couples, and should they be required to recognize same-sex marriages performed in other U.S. jurisdictions? The court will preside over 90 minutes of arguments on the first question and an hour on the second. If the justices seem skeptical about the first question, and ultimately side with the plaintiffs — there is a constitutional right to same-sex marriage, essentially — the second question won't matter much, explains Associated Press supreme court reporter Mark Sherman in this video preview.