A class-action lawsuit has been lodged against Trustmark National Bank in Shelby County, Tenn. The bank is accused of engaging in improper practices related to overdraft fees on consumer checking accounts. According to the suit, Trustmark has used these unfair practices to increase the number of overdraft fees consumers incur. White v. Trustmark National Bank was filed on April 30, 2012. The case proposes a class action on behalf of Trustmark customers in Tennessee, Mississippi, Florida, and Texas -- where the bank has a total of 186 branch offices. The suit alleges that Trustmark routinely enforces a policy that posts debit transactions to consumer accounts in order of largest to smallest by dollar amount, rather than in chronological order, to maximize the number and amount of overdraft fees. The complaint alleges that Trustmark could program its software systems to minimize these fees without added cost or risk to the bank but instead programmed its systems to manipulate transactions to maximize fee income. The suit claims that these practices are a breach of contract.