Senior Counsel, Legal Domain Expert

Join a leading AI lab's cutting-edge GenAI team to be at the core of the AI revolution, where your expertise fuels the development of the most advanced AI models.

1. Overview

We are hiring an experienced counsel-level lawyer to work directly with a leading AI lab's research and program management teams, improving how frontier AI models reason about real legal work.

This listing is for practitioners at counsel or senior associate level, with roughly 8 to 15 years of post-qualification practice. If you are earlier in your career, or if you are at partner or General Counsel level, please apply to the corresponding Legal Domain Expert listing instead, we run separate listings by seniority so the rate matches the experience.

Your legal expertise is the substance of this role. You will review the quality of legal knowledge work tasks, write the instruction specs and golden solutions that define what "correct" looks like, and build the benchmarks that show whether the model is genuinely improving. We are looking for a practising specialist rather than a generalist.

This is a full-time W-2 employment position with Cincinnatus LLC, with the opportunity to be placed at a leading AI lab as part of their extended workforce. You will be provisioned with client-issued accounts and equipment, and will work inside the client's own tools alongside their research teams.

Location: This is a hybrid role based in the Bay Area, California. You must live in the Bay Area and work on-site with the client's team multiple days each week, when required. This is not a remote role. If you do not currently live in the Bay Area, you must be willing to relocate there at your own cost before the engagement starts, relocation assistance is not provided.

2. Key Responsibilities

• Data QA and reviews: Vet the quality of legal knowledge work tasks and model outputs, spotting missing behaviors, thin reasoning, and answers that read well but would not survive professional scrutiny.

• Instruction specs and golden datasets: Write high-quality instruction specs, produce golden solutions to legal problems, and define new legal tasks that reflect how the work is actually done in practice.

• Benchmarks and domain depth: Design challenging legal tasks and evaluation sets, and help build legal-specific skills and tools together with the research team.

• Calibration: Work with client researchers and specialists in adjacent fields to keep standards consistent, translating tacit legal judgment into explicit, teachable criteria.

3. Core Qualifications

• Education: Juris Doctor (JD) from an accredited law school; a highly ranked school is strongly preferred.

• Experience: 8 to 15 years of substantive post-qualification legal practice at a reputable institution, an established law firm, a corporate legal department, a regulatory body, or a court. Internships and clerkships alone do not count.

• Seniority: Currently at or has reached counsel, senior associate, senior in-house counsel, or Assistant General Counsel level, with real ownership of matters.

• Domain depth: Genuine specialization in at least one substantive practice area, for example corporate and transactional, litigation and dispute resolution, regulatory and compliance, intellectual property, employment and labor, or tax.

• Licensure: Admission to at least one U.S. state bar, in good standing.

• AI fluency: Hands-on working use of large language models in your professional work, and the judgment to tell a well-reasoned answer from a plausible-sounding wrong one.

• Availability: Able to commit reliably to 40 hours per week for an initial engagement of 6 months.

• Location: Living in the Bay Area, California, and able to work on-site with the client's team multiple days each week, when required. Candidates not currently based in the Bay Area must be willing to relocate there at their own cost; relocation assistance is not provided.

• Excellent written communication, and the ability to give precise, well-structured written feedback.

About Cincinnatus LLC

Cincinnatus LLC is an enterprise staffing company that partners with leading technology companies to source and employ highly skilled professionals for contingent and contract-based opportunities. Cincinnatus serves as the employer of record for these engagements, providing W-2 employment, payroll, benefits, and compliance, while placing employees directly within client teams to work on high-impact initiatives.

Roles hired through Cincinnatus are not project-based or freelance engagements. They are structured, role-based positions that typically involve part-time or full-time commitments, close collaboration with a client's internal teams, and integration into standard enterprise workflows.

Cincinnatus is a legal entity separate from Mercor. While opportunities may be discovered through Mercor's platform, employment, onboarding, payroll, and benefits for these roles are administered by Cincinnatus LLC.

Equal Employment Opportunity

Cincinnatus is proud to be an Equal Employment Opportunity employer. We do not discriminate based upon race, religion, color, national origin, sex (including pregnancy, childbirth, reproductive health decisions, or related medical conditions), sexual orientation, gender identity, gender expression, age, status as a protected veteran, status as an individual with a disability, genetic information, political views or activity, or any other legally protected characteristic.

Cincinnatus is committed to providing reasonable accommodations for qualified individuals with disabilities and disabled veterans throughout the job application process.