Private equity firms are entering the US legal market by utilizing an innovative financial structure known as a Management Services Organization (MSO). This structure allows outside investors, including private equity and venture funds, to inject capital into law firms, a move previously restricted by professional ethics rules prohibiting non-lawyer shareholders. The MSO effectively splits a law firm into two parts: a lawyer-owned entity focusing on legal casework and the MSO, which houses intellectual property, technology, and all back-office functions. This model provides an influx of capital to law firms for technological investments, particularly in AI, and allows investors to participate in the lucrative legal market.

This trend is considered the "last frontier" for private equity, following similar ventures into the accounting sector. While early deals were small and regional, primarily in personal injury law, there's growing interest from full-service law firms. For example, Cohen & Gresser, a New York-based white-collar defense firm, has publicly expressed interest in bringing in private equity. The focus on private equity work by the largest law firms is causing a "profound ripple effect" across the industry, leading top firms to narrow their practice portfolios to high-fee, PE-driven transactions.

This shift has resulted in significant increases in billing rates, with Am Law 100 firms seeing over 9% growth through November, Second Hundred firms over 7%, and midsize firms a 6% increase in worked billing rates. The concentration of PE practices in top-tier firms is pushing non-PE work to other firms, sometimes at relatively lower rates. Concerns have been raised about the potential impact of private equity's commercial drive on the quality of legal advice, drawing parallels to the effects seen in the US healthcare sector.