Slaughter and May and Cravath, Swaine & Moore have joined forces for the first time to produce a research and guidance note about blockchain technology.

The report, which offers “practical guidance” on creating blockchain and distributed ledger products that are GDPR-compliant, is aimed at privacy lawmakers and the wider industry.

New York-based Cravath, one of the world’s top commercial law firms based on profit per equity partner, is historically one of Slaughters’ closest U.S. allies, alongside Paul, Weiss, Rifkind, Wharton & Garrison and Wachtell, Lipton, Rosen & Katz.

The two firms have a relationship going back “many, many, many” years, according to Slaughter and May partner Rob Sumroy. However, he said their collaboration on privacy issues is a more recent development.

Senior partners from each firm’s intellectual property and privacy teams helped co-author the report, with Sumroy, Slaughters’ tech and outsourcing head, and David Kappos, a senior Cravath IP partner, leading for each firm. Kappos was director of the U.S. Patent and Trademark Office from 2009 to 2013.

“We pick these opportunities very carefully. This isn’t a marketing pamphlet,” Sumroy said. “It’s taken months of research and analysis and significant time and effort, but we’ve done it because we thought we could do something unique.”

Sumroy said the research can be used by U.K. and U.S. lawmakers, especially as new privacy regulations emerge in the U.S. and European lawmakers begin to issue guidance on how to comply with GDPR.

He also hopes that blockchain technology companies can use it to learn how best to design their products to be GDPR-compliant.

The two firms began working more closely together a year ago when clients began grappling with GDPR, according to Kappos.

“It shouldn’t be a surprise that a top U.S. firm would be working with a top U.K. firm on something like blockchain,” Sumroy said. “GDPR is a high point in privacy regulation, but the most significant investment in blockchain technology is coming out of U.S. firms. It’s a natural bridge between the east coast states and the U.K.”

Sumroy added that when the firm helps U.S. firms, it is because firms like Cravath have the clients and are looking for a specialist in some European or U.K. legislation. “We love doing it with Cravath because they’re not on the ground in London competing with us,” he said. “If their clients need help from us, we’re there for them too.”

Kappos said Cravath has been in talks with regulators in the U.K. and the U.S. on privacy issues, and that it is an area in which the two firms will continue to collaborate, both in blockchain and other technologies such as AI—an area in which the U.S. Congress has recently shown a lot of interest, Kappos said.

Sumroy noted that the publication of the blockchain paper “is not the end of the road” in their collaboration on blockchain and privacy issues. And Kappos added that while they are not so much interested in the cryptocurrency aspect of blockchain, they “believe the enterprise and industry applications will continue to grow.”

A short version of the report has been published, with a longer report planned for the coming weeks.