WHEN JIMMY CARTER first took office, Mexican President Lopez Portillo journeyed to the White House in hopes of inaugurating a new era in U.S.-Mexican relations--an era founded on mutual respect and consultation. In the following two years, the United States has botched its chance to improve relations with Mexico by failing to follow the most basic tenets of diplomacy. For instance, without consulting Mexico, the U.S. varied tariffs on Mexican goods from month to month, making it impossible for Mexico to plan fo rappropriate levels of production.

This month, the two leaders met once again, and once again promised cooperation. But this time the Carter administration should stick by its commitments to Mexico. On moral grounds, the U.S. should always treat its less powerful allies with the same respect it accords more influential nations. And in light of Mexico's discovery of vast reserves of oil and gas, the United States would certainly not be acting contrary to its own self-interest to give Mexico the respect it deserves.

The U.S. should modify its old ways, and stop treating Mexico with condescension. Nothing but Mexico's newfound energy resources is likely to motivate American leaders to do so; nonetheless, the change is welcome no matter how self-interested the reason. The U.S. should not allow its past mistakes to shape its future policy. In the future, both nations should vigorously pursue compromise on issues such as illegal immigration, trade policy, U.S. purchase of Mexican oil and natural gas and Mexico's internal economic development.