Highlights
- Heather McMaster’s legal expertise ensures CoCounsel Legal delivers accurate, AI-ready answers grounded in trusted sources.
- Her team meticulously grades AI outputs, verifying every citation and detail for Fiduciary-Grade AI™ standards.
- Editorial and technical collaboration enables natural, reliable legal interactions for CoCounsel Legal users.
Heather McMaster, Director of Capital Markets & Corporate Governance at Practical Law, has spent over 18 years building content that lawyers depend on. Before joining Thomson Reuters, she practiced securities law in Toronto and New York City at firms like Paul Weiss. Today, she oversees a team of experienced attorneys, and her role has evolved dramatically with the next generation of CoCounsel Legal.
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From content creators to AI architects
The grading process: Three weeks for fifty queries
Bringing SEC content search to life
From content creators to AI architects
McMaster’s team maintains existing resources while ensuring content is “AI-ready,” a term that encompasses far more than making information available to an algorithm.
“We didn’t understand that at first,” McMaster reflects. “We’re like, ‘Well, everybody can read this. Our customers love it. Why do we need to change how we do it?’ But when [CoCounsel] is reading thousands of resources, you really have to make sure that there are no conflicting statements or different paraphrasings of how a provision is stated.” One editor may describe a provision one way while another describes it differently, she elaborates. If the LLM doesn’t see the difference, it may distort the two.
The solution? Eliminating duplication and improving signposting throughout Practical Law content. “If we have a checklist, and that checklist may be redundant because 90% of what’s in that checklist is already covered in other resources, we take the other 10% from that checklist and incorporate it into those other resources,” McMaster explains. “When CoCounsel goes to find the resource that discusses the issue at hand, it’s finding the one key source that has absolutely everything in it.”
This meticulous approach ensures CoCounsel Legal is the only legal AI built on Westlaw and Practical Law, reasoning from trusted authority without confusion or conflicting information.
The grading process: Three weeks for fifty queries
Creating AI-ready content is only part of the equation. McMaster’s team plays an equally important role in testing and grading CoCounsel’s outputs, a process that reveals the painstaking standards behind Fiduciary-Grade AI™.
“We write the queries, we create the documents to test, we identify what is essential to a gold star answer, and then we participate in grading the output,” McMaster says. “The grading is really critical as it permits us to see the answers surfaced for our customers.”
One set of 50 queries, she says, took a team of four attorneys, including herself, three full weeks to grade. “We don’t take the task lightly as we grade every aspect of the answer. We look at the quality, the accuracy, the SEC filing confirmation, and passage citation checking. It all takes a huge amount of time.”
This level of scrutiny stems directly from their legal backgrounds, which they all embody in their involvement supporting CoCounsel. “All of us really understand the critical importance of an accurate and timely response to clients,” McMaster emphasizes. “The work must always be verified before giving a response. There’s no room for errors at any time.”
Bringing SEC content search to life
The most concrete example of editorial impact is the team’s work on SEC content search capabilities in the next generation of CoCounsel Legal. This project exemplifies the integration of Practical Law expertise with cutting-edge AI.
The team wrote queries addressing capital markets transactions, public and private deals, corporate governance, and broker-dealer legal matters. They created test documents reflecting real-world scenarios that securities attorneys encounter. Then came the intensive grading process, evaluating how well CoCounsel Legal surfaced relevant SEC filings, Practical Law resources, and synthesized that information into actionable outputs.
“We wrote the queries and graded the output so that the best answer contains all the relevant filings and Practical Law information in the format expected by the user,” McMaster says. The results vary based on query type; some require comprehensive 15-page reports, while others demand concise tabular summaries. “We’re helping the engineers understand that for this type of a query, this is the report you want.”
Throughout the process, verification remains central. “The fact that everything is cited and verifiable, whether it’s through the SEC filing or through linking out to the Practical Law resources, is a real game changer for our customers.”
What customers will notice
When asked what customers will notice most from her team’s work, Heather’s answer is immediate: “The accuracy of the answers provided. That has always been our goal and will continue to be.”
But there’s another benefit customers will experience without necessarily seeing the work behind it: natural interaction. Because McMaster’s team ensures queries don’t need to be over-engineered, attorneys can ask CoCounsel Legal questions the way they naturally think about legal issues. The sophisticated response comes from months of editorial and technical collaboration: invisible to the end user, but essential to the experience.
“Our queries don’t look complicated,” McMaster notes, “but that’s what the lawyer would want. It doesn’t mean the output isn’t complicated. The outputs can still be complicated, but you just are not going to sit there and go, oh yeah, I got this email from a partner 10 years ago. I’m going to upload it now.”
This commitment to authentic user experience, grounded in deep legal expertise and meticulous quality standards, is what distinguishes CoCounsel Legal. Behind every accurate answer, every relevant citation, every well-formatted report lies the work of attorneys like Heather and her team—ensuring that Fiduciary-Grade AI delivers on its promise.
The next generation of CoCounsel Legal is scheduled to launch later this year. Learn more about how we’re building the future of legal AI.
The next generation of CoCounsel Legal
Go inside the making of the new CoCounsel Legal experience
Behind the build ↗
