States say trucks from Mexico pose threat to air They call for court to require studies of traffic's impact WASHINGTON, March 13 (COPLEY NEWS SERVICE) The attorneys general for California and eight other states filed briefs with the Supreme Court yesterday, opposing the Bush administration's effort to open U.S. roads to Mexican trucks without air-quality studies. The court is scheduled to hear oral arguments April 21 on the administration's request to review a lower court order that prevented Mexican trucks from using U.S. highways without the environmental studies. A decision is expected in June.