From Richard Winger over at Ballot Access News:
On March 17, the Massachusetts Libertarian Party asked the U.S. Supreme Court for an extension of time in which to file a cert petition in Barr v Galvin. Such extensions of time are fairly easy to obtain. Barr v Galvin is the Massachusetts case over whether unqualified parties have a right to use stand-in presidential candidates on their ballot access petitions, given that qualified parties have the right to change their presidential and vice-presidential nominees. For example, in July 1972, the Democratic Party certified Thomas Eagleton as its vice-presidential nominee to election officials in all states, but the following month, the party substituted R. Sargent Shriver.
Also on March 17, The Massachusetts Libertarian Party asked the U.S. District Court who had originally handled the case to certify the question (to a state court) of whether Massachusetts election law already permits presidential stand-ins. Originally, the U.S. District Court had ruled in favor of the party, and had ruled that the apparent ban on presidential stand-ins for unqualified parties violates the Constitution. Later, the First Circuit had reversed the U.S. District Court on the constitutional issue, but had suggested that perhaps the state courts should interpret whether the law really bans stand-ins or not. The law is not clear.