For more than 60 years, Leach & Sullivan, Limited Liability Partnership has been a cornerstone of the Duncan community, serving individuals and families throughout southern Oklahoma.

Our firm provides representation in all types of legal matters, including family law, criminal defense, real estate, business litigation, business organizations, banking law, personal injury, probate, estate planning, and oil and gas law.


Founded in 1954, our firm and its experienced attorneys have been serving clients throughout southwestern Oklahoma for over 60 years. Lawyers from the Sullivan family have been practicing in the Duncan area since the 1920s, and their strong commitment to the local community carries over to the present day. Follow the links below to learn more about each attorney at our firm:

When you are working through a problem within the legal system, it is important to work with a law firm that has experience handling a similar problem or case that you face. At Leach & Sullivan, we have been serving southwestern Oklahoma for over 60 years. We have built our legal practice on a foundation of competent and effective advocacy, with a commitment to giving each client the personal attention they need.

Sound Experience Matched With A Reputation For Excellence

Our longevity as a firm is built on a foundation of exceptional representation, customized legal solutions and the ability to deliver results. We are sought after throughout southern Oklahoma to represent clients in a broad range of issues, including:

Environmental issues — Our firm advocates on behalf of land owners and businesses in the southern Oklahoma area in leases, land use, water rights and other environmental law matters.

Oil and gas law — Oil and gas are cornerstones of the community, and we provide the legal representation to make sure that land owners and those working in the industry are protected.

Divorce and family law — Our firm represents clients in all types of family law matters, including divorce, child custody, child support, modifications and property division.

Criminal defense — From DUI charges to arrests for possession of drugs, we aggressively advocate on behalf of accused individuals to protect them from future-altering sentences.

Business litigation and real estate — Our lawyers represent clients who are buying or selling real estate for their business. We also help clients choose an entity and prepare the necessary documentation.

Wills and estate planning — We work with clients to help them organize their assets and determine how those assets will be distributed to beneficiaries.

Probate issues — The probate process can be emotionally challenging and legally complex. Look to a skilled attorney for the help and guidance you need.

Personal injury cases — We represent clients who suffered injuries in car crashes, oil field accidents and slip-and-falls.

From the moment you walk through the door, you are treated as family and given the same degree of excellence in legal representation that we would give our own family. We aggressively advocate to protect your family and your future.

To arrange a consultation, call 580-255-1111. Our office is open Monday through Thursday from 8:00 a.m.-noon and from 1 p.m.-5 p.m and 8:00 a.m.-1 p.m. on Fridays. We are conveniently located in downtown Duncan across the street from the old Palace Theater and next to First Bank & Trust at 921 W. Main Street.