By Brent Kendall And Emily Maltby The Justice Department on Friday formally opened its Supreme Court defense of the Obama administration's health-care overhaul, and in a twist said the recent bankruptcy of the one of the challengers bolsters one of the government's key arguments.The department submitted a 63-page written brief that reiterated its main legal arguments in support of the health-care law's requirement that individuals carry health insurance or pay a penalty.Among its submissions, the Obama administration argued the insurance mandate is a valid way to address a national crisis in which the uninsured impose huge costs on the U.S. health-care system.In a new effort to underscore that argument, the Justice Department cited plaintiff Mary Brown, a former auto-repair-shop owner from Florida. The Wall Street Journal reported last month that Ms. Brown closed her shop last year and filed for personal bankruptcy. Among Ms. Brown's liabilities are thousands of dollars in unpaid medical bills."Those liabilities are uncompensated care that will ultimately be paid for by other market participants," the department said in its brief. "As Congress found, Brown's experience is hardly atypical."Ms. Brown said in an interview Friday that she and her husband filed for bankruptcy because of the significant expenses related to her auto-repair business, not because of their medical bills. "You have to put down everything you owe," she said of the filing. "That doesn't mean I won't pay it." Ms. Brown said she was looking for a job that would enable her to afford health insurance, "but I don't want someone telling me that it's the law and that I have to have it."The Justice Department said the uninsured consumed $116 billion in health care services in 2008, and providers were not compensated for $43 billion of that total. It said the insurance requirement is a "classic economic regulation" to address that problem.Groups opposing the law also filed several briefs at the Supreme Court Friday. One was filed by 36 Republican senators, who said that if the court finds the insurance mandate unconstitutional, it should nullify the entire law. Ms. Brown was the only plaintiff the Justice Department agreed had legal standing to challenge the insurance mandate. The case also involves challenges by 26 states and the National Federation of Independent Business. Without owning a business, it could be harder for Ms. Brown to argue that the law harms her, and her financial woes suggest she could be exempt from penalties for not having health insurance. To address potential problems posed by the bankruptcy, the business federation this past week asked the Supreme Court to add two new plaintiffs to its lawsuit, and the government supported the move.The Supreme Court will hear the case in March, with a decision expected by the end of June. Write to Brent Kendall at brent.kendall@dowjones.com and Emily Maltby at emily.maltby@wsj.com ...