The most common approaches are arguing that the term has a non-surname primary significance, demonstrating acquired distinctiveness, or arguing the mark as a whole is not primarily merely a surname.
Non-surname primary significance: if the term also has an established meaning as a common word, a geographical term, a historical figure, or a coined term, argue that consumers would not primarily perceive it as a surname. This is the strongest argument if the non-surname meaning is well-established in the relevant field.
Acquired distinctiveness: submit evidence that the term has been in long and exclusive commercial use and consumers associate it with a specific brand rather than a family name. Five years of exclusive and continuous use creates a presumption; additional evidence strengthens the claim.
Rarity: if the surname is extremely rare (very few people in the US share it), argue that consumers would not primarily perceive it as a surname. Evidence of rarity through census data or surname frequency databases supports this argument.