“We only have 6,500 members, but we process more than 600 international wire transfers a year, which is a huge amount,” Crouse said.

During examinations, the credit union staff spends about half a day educating examiners about its FOM, Crouse said.

“Even beyond the wire transfer situation and opening new accounts for the expats, we have to discuss to make sure they fully understand so they don't question our lending area,” he said. “We're doing loans for expats that don't have any U.S. credit history; we're doing mortgages for expats. This is Southern California: They're significant mortgages. They (examiners) just need to understand that we were basically created 40 years ago to serve this membership, and that's just part of our deal.”

Widening the FOM might seem like a way to alleviate some of the regulatory caveats that accompany narrow FOMs, but the change might not lessen the risk of disparate impact claims.

Under the disparate impact principle, plaintiffs in discrimination cases can use statistical data to prove that a lender's policy negatively affects a protected class of consumers, even if the lender did not intend to discriminate. In a controversial decision in June 2015, the Supreme Court affirmed the use of the method in matters involving the Fair Housing Act.

The question now is whether credit unions with FOMs that tend to have dominant demographic characteristics, such as the largely male technology sector, risk disparate impact claims.

“The problem exists when you have taken on an underserved geographic area with the intent of growing your membership and perhaps increasing profitability, but you haven't served that group as you have served maybe your main geographic field of membership,” CU Direct Executive Lending Advisor Michael Cochrum said.

Credit unions need to take a hard look at their marketing habits, Cochrum noted.

“The issue becomes that they tend to market as if they're marketing to their current field of membership,” he said.

Credit unions that are changing demographically should be careful about how they treat new members versus existing members, he warned.

“You need to be cognizant that any offers you make do not show favor to one group over another,” he said.

For credit unions doing indirect lending, offering a rate discount to current members could cause trouble, for example, because nonmember applicants may be very different from the membership demographically. If the discount is not based on anything other than the fact that the applicant is a favored member, disparate impact may occur.

Even expanding the universe of auto dealerships that a credit union does business with and markets through in response to an expanding FOM could increase exposure.

“They could, in effect, be redlining because of the customers that that dealer does business with. If they say, 'Well, we're only going to do business with Mercedes, BMW and Lexus dealers because we like the collateral,' they could be creating disparate impact,” Cochrum said.

He added, “You can't just make assumptions and say, 'Well, we're getting the applications we get,' because there could be things in your policy, for example, that are preventing those applications from coming to you.”

Marvin Umholtz, president/CEO of Umholtz Strategic Planning & Consulting Services, has been worrying about the possible damned if you do and damned if you don't ramifications of unique FOMs for some time.

“As a practical matter, credit unions are stuck with this,” Umholtz said. “The vast majority of credit unions are going to be buried by the compliance-driven mindset of the regulators. It's not risk-based anymore. It's not like, where's the most likelihood for all this stuff to go wrong. Prove to me, and I'm the regulator speaking, prove to me that you have a compliance system that ferrets out every instance of the problem. Prove to me that your system is so bulletproof that nothing is going wrong.”

One way credit unions can mitigate the risk, Cochrum said, is to recheck the facts on their lending requirements. If time on the job doesn't statistically matter anymore, for example, credit unions shouldn't use it in their credit criteria, he said.

That may not be enough, though.

“I feel like our other issues that we've had across the financial services industry – not just with credit unions – is that somebody's going to, at one point, file a class-action suit,” Cochrum said.

Umholtz was even less optimistic about the notion of expanding the FOM to insulate against disparate impact – especially for smaller credit unions.

“You better start looking for a merger partner,” he said. “Besides this, you're going to get hit with higher payments for your deposit insurance because of the taxi medallions and a bunch of other things … the regulatory burden is going to land on top of you so hard you're going to surrender.”

Will disparate impact affect whether credit unions widen their FOMs? It's hard to tell. Parsons' board recently discussed expanding its FOM by adding other companies, but it decided to focus on penetrating its existing universe.

“That brings a whole different mix in where you can't really make these grey area calls like you can when you have a set type of membership,” Crouse said. “You know the company inside and out. When you have a general field of membership or a community charter, you really don't know what's going on.”