What the role means at a US firm
A lateral partner is a partner who moves from one firm to another with an established practice. At a firm of 5 to 200 attorneys, the hire usually does one of three jobs. The partner brings clients the firm does not have, fills a practice area where the firm is turning work away, or anchors a new group or office.
Firms rarely hire lateral partners on a schedule. A client need, a departure, or a growth plan opens the seat, and the firm wants the search done quietly.
The title also differs by firm. Some firms have one tier of equity partners. Others run a two-tier partnership, with income partners or non-equity partners below the equity tier. The same person can receive an offer for either seat, and the terms are very different. Part of every search is agreeing which seat is on offer.