In what situation can Mrs. Smith legally instruct a broker to sell her home only to a fellow Presbyterian?

In this situation, Mrs. Smith's instruction to sell her home only to a fellow Presbyterian represents a form of discrimination based on religion, which is generally prohibited by fair housing laws. These laws, including the Fair Housing Act and various state laws, aim to eliminate discrimination in the sale and rental of housing based on characteristics such as race, color, religion, sex, national origin, familial status, and disability.

Broker Brown cannot ethically or legally assist Mrs. Smith in executing such a preference because it goes against the principles of non-discrimination that real estate professionals are required to uphold. Engaging in or facilitating discriminatory practices not only violates fair housing laws but can also lead to serious legal consequences for both the property owner and the real estate broker.

In summary, Broker Brown's refusal to assist is in line with the legal and ethical standards that prohibit religious discrimination in real estate transactions.