In Michigan, the state suspends your driver's license if you don't pay your traffic tickets. But three weeks ago, a federal judge in Flint enjoined that practice when it's applied to the very poor, ruling that suspending licenses without ascertaining the debtor's ability to pay is likely a violation of due process.

Michigan's traffic tickets can certainly hit drivers hard in the wallet. The state's traffic fines, which begin at $150, can be accompanied by up to $100 in discretionary court costs, plus a mandatory "justice system assessment" of $40 per infraction. If unpaid within 56 days, they increase by 20 percent. Failure to pay these costs is also a misdemeanor, carrying an additional fine of up to $100. After six weeks, the secretary of state automatically suspends the debtor's driver's license until the debts are paid in full, plus an additional "reinstatement fee" of $45.

If you're caught driving on a suspended license, the costs go up further. "Driving While License Suspended" is a misdemeanor carrying a $500 fine; the reinstatement fee increases to $125, and you also face a new penalty, called a "driver responsibility fee," of either $250, $500, or $750.

Last year the civil rights group Equal Justice Under Law challenged that system in court. Suing on behalf of Adrian Fowler and Kitia Harris, two women whose licenses were suspended due to court debt, the organization's attorneys argued that the license suspension scheme infringes on a number of constitutionally protected rights, including fundamental fairness and freedom of travel. Judge Linda Parker found most of these arguments unlikely to prevail on the merits, but she held that suspending licenses without holding an "ability-to-pay hearing" (as a number of other states routinely do) probably violates drivers' rights.

The state then asked the U.S. Court of Appeals for the Sixth Circuit to indefinitely stay Parker's order. In its response, the appeals court acknowledged that "the injunction is broad in scope and provides very little direction as to what specific actions should be taken." But it added that the government is unlikely to prevail on the merits, and it has stayed the order for only 30 days—long enough for Parker to give Michigan more specific instructions on how to comply with her injunction.