The McDonnell Douglas A-12 Avenger II’s radical, wedge-shaped design still looks exotic, even in the 20 years since the program was cancelled after an outlay of billions of dollars that failed to produce even one real airplane. The proposed Navy attack bomber has fascinated me ever since the first time I saw an artist’s rendering of it.

Dubbed the “Flying Dorito” for its tailless, triangular shape, the A-12 was supposed to be a stealthy successor to the durable Vietnam-era A-6 Intruder. But after becoming mired in overruns, delays, technological missteps and inter-service rivalries, the program, which eventually cost U.S. taxpayers billions of dollars, was finally terminated by then Secretary of Defense Dick Cheney in January 1991. It was the largest weapons program ever terminated by the Pentagon.

Why do I unearth this ancient history? A recent press release from an investment firm made its way to my email inbox, alerting me to the fact that more than two decades later, the matter is still under litigation as the case made it all the way to the Supreme Court. Contractors General Dynamics and Boeing, which had acquired McDonnell Douglas in the interim, claim that the government terminated the contract illegally and that they are owed more than a billion dollars for unpaid work, while the government claims it’s owed even more in unapproved deliveries.

According to James Stevenson–author of The $5 Billion Understanding, a clinically meticulous though dry history of the program and its ongoing legal wranglings–the case is the largest lawsuit involving contractors against the U.S. government in history.

In its ruling last month, the Supreme Court overturned a 2009 decision by the U.S. Court of Appeals for the Federal Circuit that had previously upheld the U.S. Navy’s termination for default of the program. The Supreme Court upheld a key argument for the manufacturers, stating that they do not owe monetary damages to the Navy. The matter was kicked back to the lower courts.

A key issue in the A-12’s ill-fated development was the unsuccessful attempt to use composites to save weight. At the time the program was cancelled, the weight of the aircraft had ballooned by 30 percent over specification, to more than 30 tons and thus endangered its operation from carriers. In its contract termination, the government cited this, as well as delays and the airframers’ failure to make progress, as breach of contract. Under that classification, the contractors would not be paid for work performed during the three years of the program, or see a reimbursement of any money they had laid out to subcontractors. They were also instructed to return any payments previously made.

The manufacturers claim that the program was cancelled improperly at the convenience of the government, which prevented them from proceeding in the aircraft’s development by withholding crucial stealth technology.

The legal proceedings have been hampered by the government’s failure to produce requested evidence, citing possible harm to national security through the disclosure of “state secrets.” Stevenson’s analysis of this latest ruling states the government wants to have its cake and eat it too, by not presenting evidence that the contractors say will prove their case, and still demanding that they repay the money they were given, plus interest. Whether this matter churns in the courts for another two decades only time will tell.

In an ironic coincidence, a full-scale mockup of the A-12, basically the most tangible evidence of the billions spent, still exists. It is expected to be restored someday to become a prime exhibit at a planned air and space museum in Fort Worth, Texas, less than 50 miles from the headquarters of Frito-Lay, makers of the Dorito corn chip.