The Dangers of a Lateral Move

Lawyers change jobs like everyone else, but a lawyer does not leave alone. Clients, confidences, conflicts, and files all have to be accounted for, and the rules governing each are different before you give notice, on the day you do, and after you arrive. Get the sequence wrong and the consequences run from a lost offer to a visit from a partner accompanied by the police.

In this TalksOnLaw interview, Joel Cohen sits down with Sarah McShea, a New York ethics lawyer who has been a disciplinary prosecutor, a criminal prosecutor, and for decades an adviser to lawyers and firms on professional responsibility, to walk through the lateral move stage by stage.

Before You Leave: The Conflicts Check Nobody Can Run

The first problem is a paradox. A new firm needs to know what conflicts a lateral will bring, but the lateral's client information is confidential and cannot be disclosed without consent, and consent cannot be sought without tipping off the current firm. McShea describes how firms manage it: a single designated partner, walled off by written agreement, who receives limited information — client identities, the general nature of matters — that never reaches the firm's systems and is shredded if the move falls through; or, occasionally, an outside ethicist acting as what Cohen calls a reverse matchmaker, looking for reasons the parties should not be together. Even a junior associate, she notes, can carry a disqualifying conflict from a confidential merger she once did due diligence on, and a firm that discovers it after the fact may have to screen her, lose the matter, or wish it had never made the offer.

The Book of Business and the Duty of Loyalty

For senior lawyers the calculus turns on the book of business: the clients expected to follow, which determine which firms make offers and on what terms. But a partner owes her current firm a fiduciary duty of loyalty and good faith — even if the firm has treated her badly — and McShea is firm that cherry-picking clients before giving notice breaches it. Lawyers generally know which clients will follow without asking, she observes, and often move precisely because a new platform will serve those clients better. What can be said to a client before notice is, in the lawyer's answer, "it depends": a matter at a delicate stage may require some communication, but the duty to communicate is not a license to canvass the client list. After notice, clients may be told freely, without disparaging the old firm and, where possible, in a joint announcement. The same timing rule governs recruiting associates to come along.

What You Can Take

McShea is blunt about files. Client contact information belongs to the lawyer. Work product belongs to the firm, however much the lawyer's skill is embodied in it, and a departing lawyer who spends a weekend downloading deal documents will be discovered by the IT department on Monday, walked out, and potentially prosecuted for theft under state and federal law — a scenario she describes as neither far-fetched nor rare. Documents that migrated to a home laptop over the years must be returned, not deleted, because deletion does not actually remove them. There are proper ways to obtain past work from a firm that respects you, she says; self-help is not one of them.

Screens, Imputation, and the Math of a Merger

The conversation closes on the mechanics of conflicts. A lawyer's former-client conflicts are imputed to every lawyer in her new firm, and screening — isolating the lateral from the matter, the files, the emails, and the fees — is the only way to contain them. McShea explains why screens are hardest for small firms, and states New York's rule as it then stood: screening was permitted when it did not matter, and otherwise the move was barred. She then scales the problem up to a merger of two large firms, where every lawyer brings every client and the nightmare is not the conflict you can find today but the one that arrives when a major client of one legacy firm sues a major client of the other, forcing the merged firm to drop one of them.

What to Know Now

The two rules McShea flagged as unavailable in New York have since arrived, and largely on the terms she recommended. New York's Rule 1.6 and its comments now expressly permit a lawyer exploring a lateral move or merger to disclose limited information — client identities, the general nature and status of matters, the size of the book — for the purpose of detecting conflicts, subject to the same discipline she describes: no more than necessary, no contact with clients, and always mindful of the fiduciary duty to the current firm. More significantly, effective January 1, 2025, New York amended Rule 1.10 to join the majority of jurisdictions that allow a firm to avoid imputation of a lateral's former-client conflicts by promptly screening the lawyer, apportioning her no part of the fee, and giving written notice to the former client. The safe harbor does not extend to litigation or arbitration in which the lateral substantially managed the matter or had day-to-day decision-making responsibility; there, a waiver from the former client remains the only route. The New York City Bar's Formal Opinion 2026-1 offers practical guidance on the notice, its timing, and its confidentiality exception, and the same committee's Opinion 2023-1 addresses departures directly, confirming that client communications about a move generally must wait until the firm has been told. At the national level, ABA Formal Opinion 489 makes clear that a firm may not hold a departing lawyer to a fixed notice period or restrict client contact once notice is given, because the choice of counsel belongs to the client. The theft scenario McShea describes is no less real: recent cases involving departing lawyers who copied firm files have produced injunctions, disqualification, and criminal referrals. Her advice to leave harmoniously, take only what is yours, and let the clients decide has become, in most respects, the rule.