An arbitrator's recent award of pay raises amounting to more than 25 percent over six years to Boston police officers once again highlights the delicate issue of interest-group influence over state and local governments. If the pay hike stands, it would cost the city $83 million, but, more importantly, it would serve as a precedent for negotiations with other public-safety unions.

Massachusetts' collective-bargaining rules allow contract negotiations with public-safety unions to go to arbitration once they reach impasse. The result is that unions have no incentive to compromise. Here's the usual scenario: Unions make seemingly unreasonable demands, they dismiss city counteroffers, an impasse is declared and the case goes to an arbitrator, who generally splits the difference between the parties.

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Under current law, the arbitrator's award can be rejected by the city council, which would re-start the collective bargaining process. But that rarely happens in Massachusetts municipalities, because it would require many city councilors to vote against the organizations to which they owe their jobs.

One fact that speaks volumes about the state's political climate is that 18 of the 20 political action committees that give the most to candidates for state and county offices in Massachusetts are labor organizations (17 are unions and one is an association of retired public employees). While that number doesn't apply to city elections, union sway over Boston politics is even stronger than it is at the state level.

But what makes this award different is that it comes in the midst of the city's first open mayoral race in 20 years. And it may just turn out to be the defining issue of the campaign.

One of the two finalists in the mayor's race is John Connolly, who as a city councilor will have a vote on whether to accept the award. Connolly has already said he will vote to reject it.

For the other candidate, state Rep. Martin Walsh, the award presents a bigger problem. Walsh topped the mayoral ballot in the nonpartisan preliminary election thanks to a wave of union support. While serving as a state legislator, he also headed the local Building and Construction Trades Council, an umbrella organization of trade unions.

Walsh has also come out against the award, but under legislation he has long pushed as a state representative there would be nothing he could do about it. His bill would make arbitrators' awards binding, eliminating even the possibility that a city council could reject them. His best hope is that most voters remain unaware of these conflicting positions.

The Boston police arbitration award demonstrates yet again that sunlight is the best disinfectant. Because the award is an issue in a hotly contested mayoral race, it may not stand.

But these decisions rarely attract so much attention. That's why collective-bargaining rules that give either side an incentive not to bargain in good faith should be eliminated. Those that would make arbitrators' decisions binding should be out of the question.

Public officials using taxpayer money to bargain with their benefactors is a problem that can't be overstated in American politics. In some places, like Massachusetts, the benefactors are unions. In other place, they're corporate, business or other interests. One is no better or worse than the other.