Our Team
At Guffey & Kostun Law Group, we offer a comprehensive range of legal services designed to meet the diverse needs of individuals, families and businesses across South Florida. Whether you’re planning for the future, resolving a dispute or navigating a complex transaction, our experienced attorneys are here to guide you every step of the way.
Nancy Guffey
Partner
Nancy Guffey has over 30 years of legal experience. Admitted to the Florida Bar in 1993, she has built a distinguished career centered on integrity, precision and high-level advocacy in complex estate and appellate matters. Ms. Guffey is a bilingual attorney, fluent in both English and Spanish, which allows her to serve a diverse client base in South Florida. She is deeply involved in the legal community, serving on the Palm Beach County Bar Association’s Appellate Law & Practice Committee and the Probate & Guardianship Committee. Additionally, she has contributed over a decade of pro bono service to the Guardian Ad Litem Program, underscoring her commitment to compassionate representation.
Areas of Practice
Ms. Guffey’s practice is primarily focused on the following areas:
- Probate and Trust Administration
- Probate Litigation
- Wills and Estates
- Appellate Practice
Education, Titles and Honors
Nancy Guffey holds an LL.M. in International Law from the University of Miami School of Law (1995) and earned her Juris Doctor from St. Thomas University School of Law (1992). Her academic background is further distinguished by her undergraduate degree from Gettysburg College. Professionally, she is a recognized thought leader, having co-authored “Understanding Fiduciary Duty” in The Florida Bar Journal.
Kimberly Kostun
Partner, Certified Circuit And County Court Mediator
Kimberly Kostun brings over 25 years of experience as a distinguished litigation attorney and strategic adviser. Licensed to practice in Florida, Pennsylvania, and New York, she manages the firm’s Pennsylvania branch while maintaining an active presence in South Florida. Her career is marked by a transition from a long tenure at Hinman, Howard & Kattell, LLP to her current leadership role, where she continues to build on a reputation for high-stakes advocacy and detail-oriented representation.
Areas of Practice
Ms. Kostun maintains a diverse general litigation practice with a specific focus in:
- Commercial and Banking Litigation
- Creditors’ Rights and Debt Collection
- Personal Injury
- Construction and Real Estate
Education, Titles and Honors
A Florida Supreme Court Certified Circuit and County Court Mediator, Ms. Kostun is a highly sought-after neutral who facilitates alternative dispute resolution (ADR) to achieve out-of-court settlements. She graduated with high honors from St. Thomas University School of Law (J.D., 1999) and holds a 5.0 Peer Rating through Martindale-Hubbell, reflecting the highest level of professional excellence.
Her unique multistate licensure allows her to serve as a bridge for clients with legal interests spanning the East Coast. She is an active member of numerous professional organizations, including the Palm Beach County Bar Association’s Alternative Dispute Resolution Committee and the American Trial Lawyers Association.
Gordon Dieterle
Partner, Certified Circuit And County Court Mediator
Gordon Dieterle has practiced law for more than 45 years and brings sophisticated legal experience to the firm. A mainstay of the South Florida legal community, Mr. Dieterle has built a career defined by longevity, reliability and an unwavering commitment to his clients. Admitted to the Florida Bar in 1979, he provides the firm and its clients with a wealth of historical perspective and technical mastery in property and business law.
Areas of Practice
Mr. Dieterle’s practice is primarily centered on the intricate intersections of property, commerce and succession:
- Real Estate Law
- Estate Planning and Probate
- Business and Corporate Law
Education, Titles and Honors
Mr. Dieterle holds a Juris Doctor from the University of Miami School of Law (1979) and an undergraduate degree from the University of Florida. His professional standing is underscored by an AV Preeminent® Peer Review Rating through Martindale-Hubbell, the highest possible rating for legal ability and ethical standards, maintained for decades.
Beyond his legal practice, he is a dedicated member of the North Palm Beach community. His unique qualifications include a deep-seated knowledge of the local South Florida real estate market and a collaborative approach that bridges the gap between complex transactional work and long-term legacy planning.
Jeffrey Royer
Partner
Jeffrey Royer offers clients a sophisticated level of expertise backed by over 35 years of legal experience. Admitted to the Florida Bar in 1989, Jeffrey has dedicated his career to providing steady, authoritative guidance in the areas of civil litigation and real property law. His approach perfectly mirrors the firm’s commitment to clarity and high-touch representation, ensuring that complex legal matters are handled with professional precision.
Areas of Practice
Mr. Royer maintains a practice designed to protect the assets and interests of individuals and businesses in North Palm Beach and throughout South Florida:
- Civil Litigation
- Real Estate Law
- Probate and Trust Administration
Education, Titles and Honors
Jeffrey Royer earned his Juris Doctor from St. Thomas University School of Law and holds an undergraduate degree from Florida Atlantic University. He is an active member of the Palm Beach County Bar Association, where he stays at the forefront of local legal developments.
His unique qualifications stem from his deep roots in the South Florida community and his ability to translate intricate legal statutes into plain-language strategies for his clients. Jeffrey’s extensive background in litigation allows him to anticipate potential conflicts during the transactional phase, providing a layer of foresight that helps his clients avoid future disputes.