The Brighton Park Neighborhood Council and the Logan Square Neighborhood Association filed a lawsuit on Thursday against Cook County Assessor Joe Berrios, alleging that his office “systematically and illegally” shifts residential property tax burdens to minority and low-income homeowners.

The lawsuit comes after months of allegations against the assessor for undervaluing homes in majority-white and majority high-income neighborhoods.

Homes in minority and low-income neighborhoods were allegedly overvalued to make up for the disparity.

“It is fundamentally unfair that families in this community are required to pay artificially inflated taxes for their homes and bear a disproportionate share of the tax burden in Cook County,” Patrick Brosnan, of Brighton Park Neighborhood Council, said in a statement.

A joint series by the Chicago Tribune and ProPublica Illinois in June investigated that methodology and found it to be “riddled with errors.” Berrios refuted the claims and said taxpayers could appeal.

In the suit, the two community groups say under Berrios, “Cook County’s residential property tax scheme is neither accurate nor uniform — and therefore violates the Illinois Civil Rights Act, the Equal Protection Clauses of the Illinois and United States Constitutions, the Uniformity Clause of the Illinois Constitution, and the federal Fair Housing Act.”

The groups are requesting the court to declare the assessment system unlawful, and to order Berrios’ office to adopt and implement a fair, accurate and nondiscriminatory system. It also seeks the appointment of an independent monitor to oversee the process.

The assessor’s office stands by its property assessments, but could not comment further due to the pending litigation.

Berrios’ campaign manager Mario Lopez called the lawsuit “politically motivated.”

“Long before media attention turned to property assessment, the Berrios administration has been proactive in improving the system to make assessments fairer,” Lopez said in a statement. “Cook County and the assessor’s office hired Tyler Technologies to work on identifying improvements in the property assessment system at every level — a process that is still ongoing, as improving any 40-year-old system cannot be accomplished overnight.”

Democrat Fritz Kaegi, candidate for Cook County Assessor, chimed in on the matter, saying in a statement the suit “is yet another sign that Joe Berrios cannot be trusted to be our Assessor. The harmful effects are disproportionately felt in lower income neighborhoods and communities of color, and it is urgently necessary to fix this broken system.”