Two undeniable successes of Gov. Chris Christie and Democratic lawmakers who cooperated with him are the 2 percent cap on annual municipal property-tax increases and the accompanying 2 percent cap on binding arbitration awards to municipal police officers and firefighters.

The value of the 2 percent caps on property-tax increases and arbitration awards is obvious. Both are key components in holding down New Jersey's property taxes.

Yes, the state's property taxes remain the highest in the nation. But the situation would be far worse without these two measures.

The property-tax cap forces municipalities to make hard choices on spending, which is what taxpayers desperately want them and need them to do. (See the letter below from Edward Eck, who recently moved here from Texas and was shocked by the state's taxes.)

And it appears to be working. The caps have held down municipal property-tax increases, and the average increase in police and fire salaries has been 1.86 percent since the arbitration cap was approved in 2010.

But as part of the compromise that convinced Democratic lawmakers to vote for the arbitration cap despite vehement opposition from their union supporters, the law came with a sunset provision: The arbitration cap is set to expire April 1. And there are concerns that Democratic lawmakers, particularly in the Assembly, will now kowtow to union demands to kill it.

That would be a shame - or, perhaps more accurately, as Assemblyman Declan O'Scanlon, R-Monmouth, told The Star-Ledger, "a disaster."

Only police and fire contracts are subject to binding arbitration. When the two sides can't agree on a contract, an independent third-party arbitrator sets the terms.

And before the cap was enacted, those awards were made with little consideration of the town's ability to pay. The result: New Jersey police salaries, which average $91,000 a year, are the highest in the nation, according to a 2010 study by The Star-Ledger. In Edison, more than 90 percent of police officers earn more than $100,000.

Salaries in South Jersey are lower - but only slightly. And there is no doubt that, when people ask why taxes are so high in New Jersey, one key reason is the skyhigh salaries, terminal-leave benefits and other perks paid to police and firefighters.

An eight-member task force that included four union representatives was split on whether the cap should be extended. But there is no doubt that it works, and lawmakers must not go wobbly - the cap must be renewed. Even when negotiations don't go to arbitration, the cap plays a key role by putting the unions on notice that there is a hard ceiling on any salary increases. Which, of course, is exactly why police and fire unions oppose the cap.

But they have lost this battle - and rightfully so. Police officers and firefighters make very, very good money in New Jersey. A 2 percent cap on any future increases - and, by the way, pension and health benefits are excluded from the cap - is perfectly reasonable.