If we issue a Visa debit card to a sole proprietor, should we put only sole proprietor's name on the card, tonly the DBA name, or both? Are there any rules that govern how the card is titled?

If there are, they would be found in your card issuer rules. I assume you are issuing them a business debit card and not a consumer debit card.

That is correct. I've searched Visa Operating Rules and have been unable to find anything.

I did just find a statement that says, with regard to Visa Commercial Products, "that an issuer may not issue a Visa Commerical card to an individual, except as follows: employees of public or private sector companies, including sole proprietors and self employeed individuals."

If I'm reading correctly, the bank may issue a business card to an individual if they are a sole proprietor, but that it's not required. Does that seem correct?

That is what is sounds like to me.