New rules for DeKalb County government purchases will require more competitive bidding and ban unethical companies from doing business with the county.

Designed to prevent future corruption, the purchasing policy was unveiled Wednesday by Interim DeKalb County CEO Lee May and Interim Purchasing Director Scott Callan nearly a year after a special grand jury report found lax spending practices.

Government contracts were at the center of the grand jury’s investigation, which led to the indictment of suspended county CEO Burrell Ellis. When Ellis goes on trial next month, he’ll fight allegations that he inappropriately pressured contractors for campaign contributions.

The 39-page policy says competitive sealed bidding should be used for contracting whenever possible.

It also calls for an “ineligible source list” of people who may not do business with the county because of bad faith, breach of contract, a pattern of unethical behavior or a conviction of a crime involving moral turpitude. The list will be formed by a committee made up of government employees from various departments.

The policy also prohibits any attempt to influence the outcome of a contract prior to it being awarded. Companies may be disqualified from consideration if they violate the rule.