The modern structure of large corporate law firms—often referred to as “big law”—has its roots in early 20th century professional services models that were developed to meet the complex legal needs of major financial institutions and multinational corporations. These firms are typically characterized by their size, multi-jurisdictional presence, and ability to advise on sophisticated legal matters across a range of practice areas.

One influential model that helped shape big law is the “Cravath System,” named after Paul Cravath of Cravath, Swaine & Moore LLP. The system introduced several structural elements that became standard across large firms:

• Lockstep Compensation: Associates are generally paid on a uniform salary scale based on seniority, rather than individual performance. This removes internal competition over client origination at the junior levels and encourages firm-wide collaboration.
• Recruiting from Top Law Schools: Firms often focus on hiring graduates from a small number of highly ranked law schools, using structured processes such as on-campus interviews (“OCIs”) to identify candidates. The assumption is that strong academic credentials correlate with the ability to succeed in high-pressure client environments.
• Apprenticeship Training Model: New lawyers are typically trained through hands-on work under the supervision of more senior attorneys. While formal titles may not reflect seniority until the partner level, associates are often informally categorized into junior (years 1–3), midlevel (3–5/6), and senior (5/6–8+) tiers.
• Up-or-Out Promotion System: Associates are generally expected to advance toward partnership within a set timeframe, traditionally around year 7 or 8. Those not promoted often exit the firm to pursue other opportunities, contributing to high turnover rates at the senior associate level.
• Billable Hours and Performance Expectations: Associates are evaluated largely on the basis of billable hours and work quality. Meeting billing targets is typically a prerequisite for promotion and bonus eligibility.

These practices were adopted by many large firms over the course of the 20th century and remain prevalent today, though they have evolved. Some firms have moved away from pure lockstep compensation, introduced non-partnership career tracks, or created more flexible approaches to promotion and retention.

While the “Cravath model” is most closely associated with New York–based firms, similar systems exist in other jurisdictions. For example, the Magic Circle firms in the UK, the Seven Sisters in Canada, and top-ranked firms in other financial centers share many structural similarities. In most markets, compensation remains a useful proxy for identifying firms that follow the big law model, as salary scales are widely publicized and fairly standardized among peer firms.

Overall, big law firms operate as high-performance professional services organizations, offering junior lawyers intensive training, high compensation, and experience with complex legal work, but often with demanding workloads and relatively limited long-term job security absent promotion to partnership.