There are many reasons not to subsidize exports of jumbo jets as much as our government does. Here’s one: it gives an artificial advantage to the foreign airlines competing with U.S. airlines.

Reuters reports:

Delta Air Lines Inc sued the Export-Import Bank of the United States on Wednesday, renewing a legal fight over subsidies that benefit aircraft exporters such as Boeing Co and by extension non-U.S. airlines….

Delta sued in November 2011, saying Eximbank’s subsidy was arbitrary in a deal between Boeing and Air India. A judge ruled for the bank, and the case continues on appeal.

Meanwhile, Delta said it found new reason to sue under the law Congress eventually passed renewing the bank’s charter. The law requires the bank to “develop and make publicly available methodological guidelines” for use in economic analyses.

Under newly published guidelines, at least 85 percent of aircraft-related transactions will be exempt from substantive analysis, the new suit alleges.

Reminder: Obama’s Ex-Im last year dedicated 83 percent of its loan guarantees to subsidizing Boeing exports.