A ruling in the American Bankers Association's suit challenging the NCUA's Field of Membership rules may come down to a single question: What is a rural district?

U.S. District Judge Dabney Friedrich is pushing the two sides to offer their definitions, as she struggles over whether the NCUA's field of membership rules are too broad.

In issuing the rules, the NCUA said they would provide credit unions with more flexibility in determining their field of membership.

However, the ABA contends that the rules went too far and that Congress restricted community credit unions to well-defined local areas.

In holding oral arguments last week, Friedrich asked the sides discuss the “the meaning of the phrase 'rural district' based on dictionaries and other sources of common usage at the time of enactment of the Federal Credit Union Act of 1934.”

In supplemental briefs filed following the hearing, the NCUA said that Congress delegated to the agency the authority to define the terms and as a result, they do not have to conform to any other definition.

And, the NCUA contends, there is no requirement that a rural district be “relatively small,” as the ABA argues.

However, the ABA argues that the accepted definition of “rural district” is that it is a small area.