WASHINGTON (CNN) -- The Bush administration on Tuesday asked the U.S. Circuit Court of Appeals for the District of Columbia to overturn a lower court ruling requiring that the federal government redesign the nation's paper money to aid the blind in differentiating between denominations of bills.

U.S. District Court Judge James Robertson ruled last month that the U.S. Treasury Department is violating the law by keeping all paper money the same size and feel, preventing blind people from distinguishing the amount.

Robertson, in a ruling on a suit by the American Council of the Blind, ordered the feds to come up with a way to tell bills apart.

In its appeal, the Bush administration disagreed with Robertson's ruling that the blind were denied "meaningful access" to money by the same-sized bills because portable currency readers exist to help distinguish the bills. The government also said blind people can use credit and debit cards instead of cash.

The government also disagreed with Robertson's ruling that making changes would not impose an "undue burden." The government said that making any changes to the currency would interfere with mandates to guard against counterfeiting and produce a prohibitive cost.