The exclusive location, the lucrative contract terms, the investor list, and a close personal relationship between a managing partner of the restaurant and the Chicago Park District's project manager led to a formal ethics investigation, court litigation, and extensive press coverage, and ranked among the most prominent scandals of the administration of Chicago Mayor Richard M. Daley in 2005.

One of the most financially successful restaurants in Chicago, the Park Grill remains exempt from property taxes after a multi-year litigation which reached the Illinois Supreme Court.

[10] Matthew O'Malley and his brother Paul were picked to run the Clock Tower Cafe at the Sydney Marovitz Golf Course in Lincoln Park on the Chicago lakefront.

[9][10] O'Malley obtained commitments from over 80 prospective Park Grill investors,[10][15] including some of Mayor Daley's friends and neighbors.

[10] Barbara has ties to the Hired Truck Program scandal[10][18] and the blue bag recycling controversy.

[10][19] Other investors include relatives of Daley's political adviser Timothy Degnan,[10][16] two neighbors of the mayor, Ray Chin,[10][17][20] an O'Hare Airport contractor, and Rick Simon, a controversial figure who runs a janitorial business and sits on the board of the Chicago Convention and Tourism Bureau.

[10] Also among the investors was Daley's cousin Theresa E. Mintle, then the Chicago Transit Authority's director of governmental affairs[21][22] and former congressman Morgan F. Murphy, who has had business dealings with convicted labor union official John Serpico.

[10][23] Among the vendors for Park Grill was an architectural metal company owned by the son of then Chicago Alderman Burton Natarus (42nd).

[24] By the end of the year, O'Malley's team had been selected to run the restaurant, souvenir and concession stands, and a cafe in the new Millennium Park.

[10] The Park District team, including an outside consultant, spent 18 months negotiating a contract with O'Malley's group.

[10] During that time, Laura Foxgrover, a top official in the Park District department directly overseeing the deal, gave birth to O'Malley's child.

[10][13][17][24][nb 1] Prior to working for the Park District, Foxgrover had been an employee of O'Malley as director of operations[17] at the Chicago Firehouse Restaurant.

[13] Foxgrover held the title "senior project manager" at the Park District at an annual salary of $94,000.

In February 2005, Foxgrover led a five-member Park District committee that chose Clear Channel over JAM Productions to operate the new concert venue at Northerly Island on the former site of Meigs Field.

[32] On March 16, 2005, Cook County Assessor, James Houlihan's office sent Horan and O'Malley a letter notifying Park Grill that it was being assessed at $502,550 and that it would be sent a bill in the fall for 2004 property taxes.

[26] On August 5, 2005, Horan and O'Malley filed a lawsuit against the assessor, asking that a judge prohibit the county from imposing property taxes.

[26][38] The owners asserted that their contract to run Park Grill was a property tax exempt concessionaire agreement and not a taxable lease.

[31] The Chicago Sun-Times dubbed the Park Grill the "Clout Cafe"[27][41] and included the contract award process in a year-end review of 2005 Daley administration scandals.

[53][54] Daley's successor, Mayor Rahm Emanuel appointed Theresa E. Mintle, one of the Park Grill investors, as his $174,996-a-year chief of staff.

[59] Chicago Sun-Times columnist Mark Brown summarized "the Park Grill story" as Guy meets girl.

"[46]On September 24, 2015, the court ruled in favor of the Park Grill, rejecting the Emanuel administration's claims that the contract was invalid.