During his forty years of practice, Mr. Haefeli has been working with clients in a variety of matters from litigation to real estate and land use to helping with their estate plans. He has been privileged to represent clients in all New York trial and appellate courts from the Supreme Court to the Court of Appeals. He has also represented clients in the Federal District Court, the Federal Court of Appeals and the United States Supreme Court.

An established area of his expertise is representing builders and developers as well as individual homeowners in real estate and land use. He served Westhampton Beach as Village Attorney under five mayors. Clients can depend on him to advise them in their business matters: formation and continuation as well as the conclusion of their business. Clients can also depend on his expertise in Trust and Estate Planning to help them make decisions about their personal estate plans.