Just for the sake of clarification, there are two contracts that are commonly referred to as "rate lock agreements." The one addressed in the paragraph of the regulation cited by Dan is an executed agreement between the lender and the applicant as to the interest rate, discount points and any related charges, with a stated duration during which the rate, etc., won't change.
The other "rate lock agreement" is one between a lender and a secondary market investor in which the investor commits to purchasing all or part of a loan closed at an agreed-upon interest rate at an agreed-upon price. If this is the agreement your attorney is thinking of, he or she is correct.
John S. Burnett
Fighting for Compliance since 1976
Bankers' Threads User #8