For the first time since the financial crisis, the government faced off in court against a major bank over lending practices during the mortgage mania. Lawyers for the Justice Department contend that Countrywide Financial, a unit of Bank of America, misrepresented the quality of mortgages it sold to Fannie Mae and Freddie Mac, the taxpayer-owned mortgage finance giants, starting in 2007. The government said Fannie and Freddie incurred gross losses of $850 million on the defective loans and net losses of $131 million.