Warrenville, Ill.-based Navistar International Corp. on May 3 reached an agreement with the Environmental Protection Agency (EPA) that settles lawsuits the truck company had filed in March 2009 concerning the agency’s certification policies for diesel-powered trucks equipped with selective catalytic reduction (SCR).

The agreement calls for EPA to hold a public workshop or hearing to address the issues Navistar raised in its challenges before the U.S. Court of Appeals for the District of Columbia Circuit.

Navistar had asked the United States Court of Appeals in Washington, D.C. to void those polices because the EPA had adopted them without the public process required by law, but instead following input only from the SCR engine makers. In its appeal, Navistar charged that EPA is using those policies to allow SCR- equipped diesel powered trucks to operate for extended periods without any control of NOx emissions and is certifying SCR engines as meeting NOx emission requirements when they do not.

The agreement provides that EPA will engage in a public process to reexamine its policies for future 2011 and later model year engines, during which it will provide a thorough review of EPA’s policies regarding operation of SCR-equipped engines. EPA also has promised to ensure, among other things, that SCR equipped heavy duty diesel engines are designed to properly control emissions as required under applicable regulations.

EPA in the Federal Register must publish for comment the agreement before it can become final.

“We are pleased with this agreement and look forward to participating in the public process,” said Jack Allen, president of Navistar’s North American Truck Group, said in a press statement. “We believe that with full and open public participation, EPA will develop a new approach that will result in equal enforcement of the 2010 NOx requirements for all engine makers.”