Here’s the explanation from the pro-marriage equality groups:
The lawsuits allege that, on its face, Proposition 8 is an improper revision rather than an amendment of the California Constitution because, in its very title, which was "Eliminates the right to marry for same-sex couples," the initiative eliminated an existing right only for a targeted minority. If permitted to stand, Proposition 8 would be the first time an initiative has successfully been used to change the California Constitution to take way an existing right only for a particular group. Such a change would defeat the very purpose of a constitution and fundamentally alter the role of the courts in protecting minority rights. According to the California Constitution, such a serious revision of our state Constitution cannot be enacted through a simple majority vote, but must first be approved by two-thirds of the Legislature.
As a legal and constitutional matter, I am not qualified to judge this, but it doesn’t sound frivolous to me. As a political matter, I favor re-fighting this at the ballot box, not in the court.
The Dish 