Principal Engineer, CoCounsel

Thomson Reuters•Eagan, MN

8d•Hybrid

About The Position

Principal Software Engineer – CoCounsel CoCounsel is our most advanced AI offering to date – combining generative and agentic AI capabilities to help legal professionals move beyond prompting and start delegating. As a Principal Software Engineer, you will set the technical direction for the backend, AI orchestration, and identity systems that turn frontier models into reliable, secure, production-grade workflows that attorneys, in-house legal departments, and government agencies trust on real client matters every day. This role sits at the heart of the CoCounsel Legal engineering organization, partnering closely with AI/ML engineers, researchers, product, and our identity and platform teams to deliver world-class legal content and AI experiences at scale.

Requirements

Bachelor’s Degree in Computer Science, Computer Engineering, a related field, or equivalent experience.
Demonstrated experience building with AI – LLMs, agents, and retrieval – and a strong point of view on what “AI-native” software should look like.
Proven track record owning large, complex projects end-to-end: architecture, execution, rollout, and long-term operation.
Deep Python expertise and experience with production systems using frameworks like FastAPI (or similar), relational databases (PostgreSQL or equivalent), and a major cloud provider (AWS preferred).
Strong background in distributed systems: data modeling, API contracts, observability, resilience patterns, and performance tuning under load.
Hands-on experience with identity and access management – designing or integrating authentication and authorization at scale (SSO, SAML, OIDC, OAuth 2.0, RBAC/ABAC, token/session management, or comparable IAM systems).
Excellent communication skills and the ability to partner with product, design, security, and ML teams in a fast-moving environment.

Nice To Haves

Hands-on experience designing and operating agentic systems in production – tool calling, MCP servers, multi-step workflows, and orchestration around third-party and in-house LLMs (e.g., Anthropic, OpenAI), including prompt/response management, cost controls, and safety considerations.
Experience with AI-adjacent infrastructure: vector databases, embeddings, semantic search, or custom retrieval pipelines.
Opinions and experience around automated testing, reliability, and release practices for systems with non-deterministic model behavior.

Responsibilities

Participate in shaping the company’s AI platform and patterns: Define patterns for building MCP servers, designing agents, novel uses of LLMs, experimentation, and scalable infrastructure. Your decisions will influence multiple product lines, not just a single feature.
Work at real production scale: Build and evolve systems that operate over millions of documents, complex and ever-changing law, privileged client data, and thousands of concurrent AI interactions from professionals doing time-sensitive work. Considering implications to cloud costs, optimizations, etc.
Small team, big surface area: Join a tight group of senior engineers and researchers shipping quickly, with direct access to product leadership and customers. Think ownership of a startup with the runway of a public company.
Technical leadership and cross-functional influence: Lead and/or design initiatives that cut across AI, product, identity, and infrastructure. Mentor staff and senior engineers, raising the bar on AI integration practices, system design, code quality, and security across the org.
Be the expert in new model capabilities, collaborating closely with AI/ML engineers, researchers, designers, and PMs to translate industry improvements into reliable, user-facing workflows that legal professionals trust.
Help shape the team’s roadmap, technical strategy, and engineering culture – from experimentation practices to testing, rollout, and postmortems.
Help define and lead the platform integration strategy across new and existing Thomson Reuters legal systems to deliver world-class content and solutions for our customers.
Identity, access, and trust: Define how autonomous agents act on a user’s behalf safely: scoped delegation, least-privilege service identities, secrets management, and consistent enforcement of entitlements across documents, matters, and content repositories. Partner with security, platform, and compliance teams on multi-tenancy isolation, data residency, privilege protection, and the audit trails that legal and government customers require.
Consider the design and evolution of authentication and authorization across CoCounsel Legal – SSO/federation (SAML, OIDC, OAuth 2.0), token and session management, and fine-grained, role- and attribute-based access control (RBAC/ABAC).
Scale, reliability, and performance: Design for high-throughput, low-latency AI workloads: caching, queuing, rate-limiting, model failover, and cost/performance trade-offs.
Work with large-scale data: millions of documents, retrieval and search, vector stores, and indexing strategies tailored to legal use cases.
Establish and refine SLOs, observability, and incident response for AI systems that must be correct, auditable, and trustworthy in professional legal workflows.

Benefits

Hybrid Work Model
Flexibility & Work-Life Balance
Work from anywhere for up to 8 weeks per year
Career Development and Growth
Flexible vacation
Two company-wide Mental Health Days off
Access to the Headspace app
Retirement savings
Tuition reimbursement
Employee incentive programs
Resources for mental, physical, and financial wellbeing
Globally recognized, award-winning reputation for inclusion and belonging, flexibility, work-life balance, and more.
Two paid volunteer days off annually
Opportunities to get involved with pro-bono consulting projects and Environmental, Social, and Governance (ESG) initiatives.
Market competitive health, dental, vision, disability, and life insurance programs
Competitive 401k plan with company match
Competitive vacation, sick and safe paid time off
Paid holidays (including two company mental health days off)
Parental leave
Sabbatical leave
Optional hospital, accident and sickness insurance paid 100% by the employee
Optional life and AD&D insurance paid 100% by the employee
Flexible Spending and Health Savings Accounts
Fitness reimbursement
Access to Employee Assistance Program
Group Legal Identity Theft Protection benefit paid 100% by employee
Access to 529 Plan
Commuter benefits
Adoption & Surrogacy Assistance
Access to Employee Stock Purchase Plan