Common Pleas Court Judge R. Stanton Wettick Jr.'s decision yesterday to toss out Allegheny County's base-year assessment system is the latest step in a 37-year history of assessment controversy as elected officials and property owners struggle to find a system that fairly determines how much property is worth for tax purposes. Here are the highlights:

1970 -- Green Tree Borough filed suit challenging the county's system of assessing one-third of the county every year, claiming that was unfair to all three areas.

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1977 -- Wilkinsburg filed a similar suit.

1979 -- Common Pleas Judge Nicholas P. Papadakos took control of the cases.

Oct. 1, 1979 -- Judge Papadakos brokered a consent decree that eliminated the annual regional assessments and required the county to assess every property on a regular basis.

Oct. 17, 1982 -- Judge Papadakos ends court oversight of the assessment system because the changes resulted in "fair, equitable and uniform assessments."

Feb. 13, 1992 -- A computer-aided study of 500,000 properties by the Pittsburgh Post-Gazette finds the values of many of them are substantially out of whack compared to their purchase price.

January 1994 -- An effort to address assessment problems results in substantial increases in property values -- some more than 40 percent -- leading to a taxpayer revolt.

Jan. 1, 1996 -- Fueled by the assessment controversy, Republicans Larry Dunn and Bob Cranmer give their party majority control of the county commissioners for the first time in six decades. Their first day in office they freeze assessments for five years so the county can fix the system.

May 13, 1996 -- Six homeowners file suit against the assessment freeze, claiming it unfairly freezes values at inaccurate levels.

April 15, 1997 --Judge R. Stanton Wettick Jr. declares the freeze illegal and orders the county to prepare a plan to begin developing a new assessment for implementation in 1998 for properties whose values are more than 20 percent above or below fair market value.

Jan. 9, 1998 -- In exchange for the county implementing a full reassessment by 2001 instead of 2002, Judge Wettick puts off changes for properties more than 20 percent off of fair market value but also orders across-the-board assessment increases of 2 percent for every property in the county for 1999 and 2000.

Feb. 10, 1998 -- County hires Sabre Systems and Service of Miamisburg, Ohio, to complete the countywide reassessment for $23.9 million.

Jan. 1, 2000 -- Republican Jim Roddey, elected as the first county chief executive, inherits the assessment mess.

Jan. 9, 2001 -- The county Property Assessment Oversight Board certifies new values for 552,000 properties at $57.1 billion across the county, up 48 percent from 2000. This leads to more than 90,000 appeals.

Jan. 2, 2002 -- The new county assessment figures show an overall increase of 11 percent, again leading to more than 90,000 appeals.

Jan 24, 2002 -- Mr. Roddey and County Council say they will institute a three-year waiting period before the next county assessment.

Nov. 4, 2003 -- Cmpaigning largely on problems generated by new assessments, Democratic county Controller Dan Onorato defeats Mr. Roddey.

Feb. 15, 2005 -- Responding to proposed new assessment figures for 2006 that would have nearly 80 percent of homeowners facing an assessment increase -- 17,000 of them 100 percent or more -- Mr. Onorato proposes to cap increases at a maximum of 4 percent.

May 12, 2005 -- Judge Wettick rules the 4 percent cap is illegal, claiming it would only "exacerbate" disparities in the 2003 assessment.

Sept. 20, 2005 -- Mr. Onorato announces revised assessment figures for 2006 that call for average residential increases of 5.8 percent.

Oct. 4, 2005 -- In a surprise move, Mr. Onorato decides not to use the revised figures for 2006 and instead called on County Council to establish 2002 as a base year for assessments, putting the county in line with most other counties that use a base year and adjust assessments to meet values in the base year.

Oct. 27, 2005 -- Kenneth Pierce of Braddock and Stephanie Beechaum of the Hill District file suit against the base-year system, saying their properties have decreased in value since 2002.

Oct. 31, 2005 -- A second group of homeowners file suit to challenge the base-year system.

March 16, 2006 -- Judge Wettick rules that state law allows the county to use a base-year system for property assessment, but he allows attorney to challenge the constitutionality of the state law.

June 6, 2007 -- In a landmark decision, Judge Wettick rules the state law allowing counties to use a base year for property assessments is unconstitutional because it doesn't treat all taxpayers uniformly, which is a primary requirement.