Two Am Law 100 firms that have put a premium on Canadian expansion in recent years have landed lead roles on the $2.9 billion sale announced Friday of Canada’s largest energy transmission company to the energy unit of Warren Buffett’s Berkshire Hathaway.

Dentons rapidly expanded its Canadian presence earlier this year by taking on 46 lawyers from crumbling Heenan Blaikie. That helped the firm grab the lead role advising MidAmerican Energy Holdings, which earlier in the week announced it would officially change its name to Berkshire Hathaway Energy prior to its purchase of Calgary-based AltaLink from Canadian engineering and construction giant SNC-Lavalin.

Allen Garson, a former member of the executive committee and top corporate partner at Montreal-based Heenan Blaikie, joined Dentons in February. He’s leading a team from his new firm advising MidAmerican that includes corporate partner Gavin Sinclair and associate Andrew Bourns. Garson was unavailable for comment on the potential challenges in working on the deal at both firms.

Berkshire expects the transaction to close by early next year, pending regulatory approvals. Douglas Anderson serves as general counsel for Des Moines–based MidAmerican, which Berkshire bought back in 1999. The acquirer will use the AltaLink deal to expand its electricity and natural gas transmission operations into energy-rich western Canada.

Norton Rose Fulbright, a 3,800-lawyer Swiss verein created last year through the merger of London-based legal giant Norton Rose and Am Law 100 firm Fulbright & Jaworski, is advising SNC-Lavalin on its sale of AltaLink. SNC-Lavalin paid $215 million three years ago to acquire full control of the company from an infrastructure fund owned by Australian financial services giant Macquarie Group, but the Montreal-based parent began taking steps last year to unload its infrastructure assets.

Eric Stevens, cochair of the Canadian M&A group at Norton Rose, and business law chair Stephen Kelly are leading a Montreal-based team from the firm handling SNC-Lavalin’s sale of AltaLink. Other Norton Rose lawyers working on the matter include energy regulatory partner L. Bernette Ho, senior antitrust partner Richard Wagner, securities partner Elliott Shapiro and associates David Crandall, Mathieu Deschamps and Marly Ochmann St-Jean.

Norton Rose first expanded into Canada in 2010 through its merger with Ogilvy Renault, a longtime legal adviser to SNC-Lavalin. Norton Rose subsequently absorbed Calgary-based Macleod Dixon in late 2011. SNC-Lavalin retained Norton Rose in 2012 to advise the company on an investigation into claims that a former senior executive had inappropriate ties to ousted Libyan dictator Muammar el-Qaddafi in an effort to secure lucrative Libyan government contracts. SNC-Lavalin sued that executive and a former consultant last year in an effort to recoup millions paid to decorate a Toronto apartment for one of Qaddafi’s sons.

Vice president of legal affairs Michel Jodoin took the lead in-house on the AltaLink sale for SNC-Lavalin, whose general counsel is Rejean Goulet. Last year the company hired attorney Andreas Pohlmann from German industrial giant Siemens to be its new chief compliance officer. Pohlmann stepped aside on March 1 of this year to move into a consulting role, as SNC-Lavalin hired former Dow Chemical associate general counsel and director of ethics and compliance David Wilkins to replace him. Zora Lazic serves as general counsel for Calgary-based AltaLink.

As for Berkshire, the Omaha-based holding company for Buffett’s business empire has long turned to Munger, Tolles & Olson for outside counsel. Name partner and American Lawyer Lifetime Achiever Ronald Olson sits on the company’s board of directors and firm namesake and billionaire Charles Munger serves as Berkshire’s vice chairman. But since being taken over by Berkshire in 1999, MidAmerican has kept its own deal counsel.

The Berkshire affiliate has traditionally turned to Gibson, Dunn & Crutcher energy and infrastructure cochair Peter Hanlon for transactional work. Hanlon, who joined the firm in 2011 from Willkie Farr & Gallagher, advised Berkshire on its $9.15 billion cash-and-stock acquisition of MidAmerican and over the past 15 years has advised the latter on its unsuccessful $4.7 billion bid for Constellation Energy Group in 2008, as well as its acquisitions of Arizona’s Topaz Solar Farm in late 2011 and California’s Antelope Valley Solar project in 2013.

The Am Law Daily also reported last year on Hanlon’s role counseling MidAmerican on its $5.6 billion buy of NV Energy, Nevada’s largest electric utility. Hanlon also had a small role as U.S. counsel to MidAmerican on its entry into Canada through its proposed AltaLink acquisition.

U.S. lobbying records show that MidAmerican has paid $340,000 to Hunton & Williams since late 2009 to advise on federal energy and climate change legislation.