President Obama touts the bailout of General Motors and Chrysler as one of the signature successes of his administration. He argues that the estimated $23 billion the taxpayers lost was worth paying to avoid massive job losses. However, our research finds that the president could have both kept the auto makers running and avoided losing money.

The preferential treatment given to the United Auto Workers accounts for the American taxpayers' entire losses from the bailout. Had the UAW received normal treatment in standard bankruptcy proceedings, the Treasury would have recouped its entire investment. Three irregularities in the bankruptcy case resulted in a windfall to the UAW.

First, GM and Chrysler owed billions of dollars to the union's Voluntary Employee Beneficiary Association (VEBA) when they went bankrupt. The union and the auto makers created VEBA in 2007 to assume responsibility for the UAW's generous retiree health benefits. The benefits allowed UAW members to retire in their mid-50s with minimal out-of-pocket health-care expenses for the rest of their lives. GM owed $20.6 billion and Chrysler owed $8 billion to VEBA as unsecured claims.

A bedrock principle of bankruptcy law is that creditors with similar claims priority receive equal treatment. If you owe $1,000 each on two credit cards, in bankruptcy you cannot choose to pay $900 to Citi and only $200 to Chase. Each of the creditors is entitled to an equal percentage recovery.

In the auto bankruptcies, however, the administration gave the unsecured claims of VEBA much higher priority than those of other unsecured creditors, such as suppliers and unsecured bondholders.

At the time of bankruptcy, GM owed these unsecured creditors $29.9 billion, for which they received 10% of the stock of "new" GM, which went public in November 2010, and warrants to purchase 15% more at preferred prices. Yet VEBA got 17.5% of new GM and $9 billion in preferred stock and debt obligations. Based on GM's current stock price, VEBA collected assets worth $17.8 billion—$12.2 billion more than if the administration had treated it like the other unsecured creditors.

The same thing happened at Chrysler, only to a greater degree. Chrysler's junior creditors recovered none of their $7 billion in claims. In normal bankruptcy proceedings, the UAW would have also collected nothing. Instead it walked away owning almost half of new Chrysler and a $4.6 billion promissory note earning 9% interest. Had the stock and note gone to the Treasury instead, the bailout would have cost taxpayers $9.2 billion less.

United Auto Workers President Bob King (left) with President Barack Obama at a UAW conference in Washington, D.C., Feb. 28. Getty Images

The administration also insulated the UAW from most of the sacrifices that unions usually make in bankruptcy—at taxpayer expense. Section 1113 of the Bankruptcy Code enables reorganizing companies to improve their post-bankruptcy competitiveness by renegotiating union contracts to competitive rates. In April, for example, American Airlines proposed using this power to bring down its labor costs to the level of its rivals, just as Delta and United had in earlier bankruptcy filings.

The administration decided not to do this at GM. The UAW did accept sharp pay cuts for new hires. But they only made modest concessions for their existing members, like eliminating the much-maligned Jobs Bank that paid workers even when they were laid off.

As a result, GM still has higher labor costs ($56 an hour) than any of its competitors. Indeed, Steven Rattner, the Obama administration's former "car czar," told the Detroit Economic Club last December, "We should have asked the UAW to do a bit more. We did not ask any UAW member to take a cut in their pay."

Had bankruptcy brought GM compensation in line with its competitors' (approximately $47 an hour), we estimate the resulting savings would have increased the value of the taxpayers' stake in GM by $4.1 billion. This would still leave UAW members making 40% more than the average American manufacturing worker.

Finally, GM's decision to assume certain pension obligations of Delphi, the bankrupt former GM subsidiary, also increased the cost of the bailout. New GM no longer had an obligation to support Delphi's pensions. Yet it decided to spend $1 billion to top up the pensions of Delphi's UAW retirees. Delphi's nonunion retirees and retirees in other unions did not fare so well. GM gave them nothing.

Why GM gave $1 billion of bailout funds to employees of a different company it owed no legal duty to remains a mystery. The inspector general for the Troubled Asset Relief Program is investigating whether the administration pressured GM to give the UAW special treatment, but the IG lacks subpoena power to force officials to testify. It may take a congressional investigation to establish what happened.

We estimate that these three irregularities increased the cost of the bailout by $26.5 billion. The Treasury expects the auto bailout to ultimately cost taxpayers $23 billion. The funds diverted to the UAW account for the taxpayers' entire net loss.

Avoiding these losses would have been straightforward. If the government treated the UAW in the manner required by bankruptcy law, it could have given the stock and promissory notes to the Treasury instead of to the UAW. Labor cost savings and not supporting Delphi pensions would have increased the value of the taxpayers' shares of GM, while GM would have needed less financing.

Instead, President Obama gave over $26 billion to the UAW—more money than the U.S spent on foreign aid last year and 50% more than NASA's budget. None of that money kept factories running. Instead it sustained the above-average compensation of members of an influential union, sparing them from most of the sacrifices typically made in bankruptcy. Such spending does not serve the common good. President Obama did not bail out the auto industry. He bailed out the United Auto Workers.

Mr. Sherk is a senior policy analyst in labor economics at the Heritage Foundation. Mr. Zywicki is a law professor at George Mason University and a senior scholar at the university's Mercatus Center. This op-ed is adapted from a longer article published this week at Heritage.org.