LOS ANGELES -

A lawsuit filed by the city of Ontario seeking to wrest control of Ontario International Airport from Los Angeles will face its first legal hurdle today when a Riverside County judge considers motions by the defendant to summarily dismiss the case.

Los Angeles World Airports, a municipal agency that also runs Los Angeles International and Van Nuys airports, is challenging the validity of Ontario's claims of breach of contract by LAWA, which has been in control of the Ontario airport since 1985. The respondents maintain there is no evidence of a failure to faithfully manage the facility.

Ontario wants the Joint Powers Agreement that placed the airport under LAWA's regional authority dissolved, alleging that the agency -- and by extension, the city of Los Angeles -- has neglected the field and left it at a 

competitive disadvantage by keeping ramp fees high while lowering them at Los Angeles International Airport in order to draw more traffic to that facility.

Ontario filed its suit in June after negotiations between officials from LAWA and Ontario hit an impasse. One of the chief stumbling blocks is L.A.'s request for a $475 million payment to surrender control of Ontario Airport. 

According to LAWA, nearly $500 million has been invested in runway and other terminal upgrades since the late 1990s.

Supporters of the ``Set Ontario Free'' campaign have offered $246 million.

Most inland governing bodies, including the Riverside City Council, back an independent Ontario Airport. Last year, the Ontario International Airport Authority was formed to handle a transfer of ownership.

The OIAA commissioned a study indicating that, without steps to increase the airport's visibility through general promotional campaigns and direct marketing to airlines, the field's future prospects will continue to dim.

Passenger loads at the airport have fallen 40 percent -- from 7.2 million to 3.9 million annually -- since 2007, according to the study, which noted that at the current rate, passenger levels will fall below 2 million by 2024, costing the regional economy an estimated $430 million in annual economic activity.

LAWA officials say Ontario's decline corresponds with the Inland Empire economy's overall slide beginning in 2008.

Negotiations with the administration of former Los Angeles Mayor Antonio Villaraigosa on an ownership transfer had stalled by the time he left office.

But Set Ontario Free campaigners sounded an optimistic note about the possibility of reaching an agreement with Mayor Eric Garcetti, who recently replaced all but one of the seven members of the city Airport Commission. All parties have agreed publicly that a negotiated deal is preferable to litigation.