Diana Manning is certified by the New Jersey Supreme Court as a Civil Trial Attorney and has more than three decades of experience representing clients in complex commercial litigation, legal ethics, and professional liability matters. She is also an active appellate advocate who has appeared nine times before the New Jersey Supreme Court. A leader with extensive law firm management experience, prior to joining McCarter & English, Diana served as the managing principal of the national law firm where she practiced for more than 26 years.
Diana has deep experience advising attorneys, law firms, and corporate legal departments on ethics and compliance issues, including conflicts of interest, attorney advertising, and the unauthorized practice of law. She also counsels lawyers facing disciplinary charges and ethics investigations, and defends lawyers in professional liability actions.
Her experience includes serving as lead counsel in a high-profile New Jersey Supreme Court case addressing payment of referral fees and handling a case before the New Jersey Appellate Division addressing the intersection of constitutional law and attorney regulation that resulted in a published opinion. She is the author of the New Jersey chapter of The Law of Lawyers’ Liability: Fifty-State Survey of Legal Malpractice (ABA/First Chair Press),which provides an overview of the laws governing professional responsibility in each state.
An experienced appellate advocate, Diana regularly advises clients on appellate strategy, preservation of issues for appeal, and post-trial proceedings. Her appellate practice spans commercial disputes, professional liability matters, and issues of significant importance to the legal profession.
Diana also represents clients in a broad range of complex commercial litigation matters, guiding businesses through high-stakes disputes efficiently and effectively. Drawing on decades of courtroom experience, she provides practical guidance on litigation risk, dispute resolution strategies, and business conflicts. With deep connections throughout the legal community, she is often retained as local counsel or co-counsel in matters pending in New Jersey.
An active leader in the New Jersey legal community, Diana currently serves as First Vice President of the New Jersey State Bar Association and is slated to become the organization’s President in 2028. She served on the New Jersey Supreme Court’s District XA Ethics Committee for 10 years, including serving as Chair from 2017-2019. Diana is a Past President of the New Jersey Women Lawyers Association, the Trial Attorneys of New Jersey, the Morris County Bar Association, and the Morris County Bar Foundation. She regularly writes and presents on business litigation, legal ethics, and professional liability topics.
