PHOENIX, AZ - People who bought alternative fuel vehicles can't sue because the state later rescinded their tax credits, the Arizona Supreme Court has ruled, according to the Capitol Media Services. Without comment, the justices refused to overturn an appellate court decision that people who bought vehicles in 2000 - before the Arizona state legislature rescinded the law - did not have a "vested right" to the generous tax credits that were in effect at the time. Technically, the ruling affects only one of a multitude of claims filed after lawmakers altered the law to prevent the further loss of state funds. The ruling saves the state potentially hundreds of millions of dollars. Five years ago, the Arizona state legislature approved a dollar-for-dollar tax credit for the cost of buying and converting cars and trucks that can run on something other than gasoline. That law also entitled those who buy larger vehicles to a minimum of $30,000 in credits. Eight months later, legislators realized the law not only could cost the state $800 million – 80 times more than estimated – but was flawed: It did not require the vehicle owners to actually buy anything other than gasoline. The amended law required proof of the use of some other fuel and that the owners actually kept a vehicle at least 36 months.