For almost a decade now, Allegheny County Common Pleas Judge R. Stanton Wettick Jr. has been preoccupied with fundamental questions regarding the system of property valuation in this county.

The most essential one -- whether Allegheny County should do consistent reassessments of its real estate -- was settled early this year when the Pennsylvania Supreme Court threw out the county's base-year property valuation system and ordered the county to do a reassessment.

And now comes the day of reckoning.

Today, Judge Wettick will hear from lawyers representing the county and the residents that sued the county over its property valuation system to set in motion a reassessment that most likely will affect all 570,000 property owners in Allegheny County.

County officials, who have consistently portrayed a reassessment as a back-door property tax increase, want Judge Wettick to give them a two-year window because they say the county is in no position to conduct a reassessment.

"Timing is critical. We need at least two years to conduct data collection, to do a property sales ratio study, identify areas and neighborhoods where property values are out of sync, and then give property owners an informal hearing on the assessment of their property. All of this is going to take a lot of time," said county Manager Jim Flynn.

Beyond that, officials contend the county doesn't have the financial resources -- about $30 million that county officials say they need to pay for a reassessment -- or the manpower in the county's Office of Property Assessment to conduct a reassessment.

But Pittsburgh attorneys Ira Weiss and Donald Driscoll, who challenged the legality of the county's base-year system, said the county again is trying to put off the inevitable.

"They are trying to use their own inaction and the decimation of the county's assessment office over the years to say they can't do a reassessment. I think that's an audacious position to take in this case," said Mr. Weiss.

He and Mr. Driscoll want Judge Wettick to implement an interim property revaluation that would build upon the results of a property reassessment the county conducted in 2005. The results of that assessment were thrown out by County Executive Dan Onorato because it would have increased property values by an average of 17 percent.

"We are not asking the court for a full reassessment this year. We are asking for interim relief to substantially correct a system that is profoundly unfair," said Mr. Driscoll. "We believe that the data they have now is adequate."

Both Mr. Driscoll and Mr. Weiss hope Judge Wettick will order the county to do some kind of short-term assessment for the 2010 tax year and then order the county to do a more comprehensive one in 2011 or beyond.

"Fundamentally, this has to happen because the county has failed to do what the law requires. They have spent the last few years scaring people about reassessment," said Mr. Weiss.

Allegheny County's base-year system -- which sets property assessments based on the value of property in 2002, including new construction -- is inherently unconstitutional, the Supreme Court ruled, because it violates the uniformity clause of the Pennsylvania Constitution.

To that end, the court cited examples of what has happened to property taxes in the Woodland Hills School District since the county implemented its base-year system. Between 2002 and 2005, for example, the court showed that property values in Braddock declined by 16 percent while they went up by 35 percent in Edgewood.

That inequity can be corrected if the county used the data it collected for a reassessment in 2005 and incorporated it with property sales data since then to establish a fair system of property valuation, said Mr. Driscoll.

County officials contend that is not what the Supreme Court ordered.

"The court ordered a full property reassessment, and in order to do that we have to go and visit all the land parcels in Allegheny County," said county Solicitor Mike Wojcik.

Dominick Gambino, manager of the county Office of Property Assessments under former County Executive Jim Roddey, contends that county officials have consistently made a specious argument by claiming they don't have ample data to conduct a reassessment in a short period of time.

"The county has an Office of Property Assessment. They have assessors who are out in the field every day looking at all kinds of property and updating their records. It is absurd for them to claim that they don't have data on the changes in property when they get building permits all the time. It is through building permits that they know what property owners are doing," said Mr. Gambino.

"There is no need for them to walk around to see what has happened to every piece of property. They already know what has or hasn't changed with property," added Mr. Gambino, who oversaw the county's last full-scale property reassessment in 1999.

But even though they agreed that building permits are a measure of some activity in the building market, both Mr. Flynn and Michael Suley, the current manager in the Office of Property Assessment, said there are other factors to consider.

For one thing, building permits are not necessarily required in all municipalities for property owners to make enhancements that could change the value of property, they said, and there are other changes and factors beyond construction that affect the character and value of property in a neighborhood.

"One thing is for sure," Mr. Flynn said. "If we have to do a reassessment, we're going to go out there and do the best reassessment we can."

By the same token, however, Mr. Flynn and Mr. Wojcik indicated the county may well appeal Judge Wettick's decision on a timeline.

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