Once Nassau County stumbled back into fiscal crisis mode, it was inevitable that the county’s police contract would emerge as a key obstacle to recovery. The current Police Benevolent Association campaign against County Executive Edward Mangano’s precinct consolidation plan marks the escalation of a conflict whose outcome could determine the county’s financial viability for many years to come.

Unaffordable public employee union contracts are a problem all over New York. But the Nassau PBA contract is extraordinarily costly and inefficient, even absent the fabulously lucrative buyouts Nassau wants to give some veteran officers to go away. Median pay for Nassau officers as of 2011 was $150,000 — 46 percent above the median for teachers, administrators and other professionals in Nassau school districts, who are among the best-paid K-12 educators in the country.

Once Nassau’s cops retire — after as few as 20 years on the job — they continue to receive free taxpayer-funded health insurance on top of generous pensions, which are further inflated by late-career overtime and severance pay. Of the 1,652 New York State and Local Retirement System members entitled to pensions of more than $100,000 as of fiscal 2011, fully 22 percent (371) were former Nassau police officers.

A handful of other police agencies in downstate New York — including Suffolk County’s — had pay levels rivaling those of Nassau. In Nassau’s case, however, high compensation costs are tied to work rules designed to confound any attempt to boost productivity.

For example, Nassau police are entitled to six weeks vacation, a week of personal time, time off for blood drives, and up to five weeks of sick time. Indeed, officers get so much leave they “have the flexibility to work less than half time,” the accounting firm of Grant Thornton told the Nassau Interim Finance Authority in a report last September.

Grant Thornton highlighted work rules requiring that personal leave requests be approved unless there are already two precinct posts filled by overtime; that vacation slots be awarded on the basis of seniority, regardless of shift; and that the department allow as much as 9 percent of the force to be on leave on any given day. The county is also restricted in its ability to assign police officers to other precincts. The department’s unique “minimum manning” standard, which requires that all but two posts be filled during every shift in every police precinct, is at least being challenged under Mangano’s proposed precinct reforms.

How did things ever get this crazy? County officials, going back decades, deserve most of the blame. But a key enabling factor was a 1974 state law requiring binding arbitration of contract impasses involving police and firefighter unions.

The arbitration option — invariably invoked by unions, not management — made it easier for politicians to duck their responsibilities by deferring to “impartial” (but often union-friendly) arbitrators.

Because arbitration awards often are based on salaries in adjoining jurisdictions, the law had a ratcheting-up effect on police and firefighter pay across the state. When overtime-inducing work rules are baked into the contractual pie, arbitration makes it more difficult to extract them.

Unions were also strengthened by the state’s 1983 Triborough Amendment, which mandates that all union contract provisions remain in effect after a contract expires. Triborough is a permanent law, but the arbitration provision is due to expire July 1, 2013. If Gov. Andrew M. Cuomo wants to prevent more Nassau-style messes, he’ll signal soon that he intends to block an extension.