Seems like this is a direct disenfranchisement of MA voters. How can this stand judicial review?
The Constitution states in Article 2, Section 1: Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors, equal to the whole Number of Senators and Representatives to which the State may be entitled in the Congress:
You don't even have to have a popular vote in the state for the electors. The legislature could (and many states did in the early years of our history) just select the electors itself.
About the only Constitutional question is the agreement between states voting for this an illegal compact without congressional approval?