In an ideal world, local governments would not have to assess properties for the purpose of calculating their tax bills. But in a state that relies on property taxes, among other things, to fund police, fire-fighting, education, road maintenance and other basic services -- it's essential that the property assessment system be fair.

That's not the case in Allegheny County, which has moved to the base-year method under Dan Onorato. When the county chief executive declared that 2002 would become the "base year" for property assessments, many owners were thrilled. No longer would they face periodic reassessments that raise their valuations to present market values -- the value their property had in 2002 would be the value that is calculated with the millage rate to determine their tax bill.

While that gives a break to people with rising property values, it penalizes those whose property values decline. The latest lawsuit filed against the Onorato program crystallizes the unfairness of the base-year method.

James P. and Jennifer Daugherty bought a house on Todd Street in Wilkinsburg for $31,500 in 2004. The county, however, assessed the value at $66,900 in 2002 -- the year that now passes for real-estate reality in Allegheny County. What's more, the appeals board is barred from cutting their assessment to the actual sales price.

That's unfair to the Daughertys and to many taxpayers in communities with declining real-estate values. It forces them to pay more than their fair share of property taxes, which seems to us a violation of the state constitution's uniformity clause.

We're glad they filed suit and we hope it exposes the fallacy of fairness in the base-year method. People deserve cost-effective government and low taxes, but at the heart of it they deserve an assessment system that's fair.