DETROIT — For eight years, the shell of prebankruptcy General Motors has lingered on in the form of “old G.M.” — first as a corporate entity and now as an obscure trust designed to settle debts and claims left over from the company’s huge financial collapse.

With the help of a $50 billion government bailout in 2009, a reborn G.M. emerged from the bankruptcy process as a healthy company. Meanwhile, old G.M. — officially called Motors Liquidation Company — had the task of selling off factories and other leftover assets to compensate legions of creditors.

But just as the business of old G.M. seemed to be winding down, the company has suddenly been thrust into the legal battle over responsibility for the worst safety scandal in the automaker’s history.

Last week, the trust negotiated a deal for victims of the automaker’s defective ignition switches, which have caused 124 deaths and prompted the recall of millions of small cars in 2014. The switches had a tendency to turn off by themselves, leaving the car without power and disabling its airbags.