Clarke has practised exclusively in the area of litigation and dispute resolution since 1980, following a clerkship with Chief Justice Laskin at the Supreme Court of Canada. He has represented clients in domestic and international arbitrations and mediations, at all levels of the courts in Alberta, the Federal Court, the Tax Court and the Supreme Court of Canada. The disputes on which Clarke has acted have involved a broad range of subject matters, including Aboriginal (government side), contractual and joint venture, fiduciary duties, oil & gas, corporate securities, directors' & officers' liability, shareholder remedies, professional negligence, products liability, intellectual property and tax. Cited by The Lexpert/American Lawyer Guide to the Leading 500 Lawyers in Canada, Lexpert Guide to the Leading US/Canada Cross-Border Litigation Lawyers, Chambers Global, Acritas, Who's Who Legal: Canada for Arbitration, Energy and Litigation, Benchmark Canada and The Best Lawyers in Canada, and was inducted in 2009 as a Fellow of the American College of Trial Lawyers. Martindale-Hubbell rates him AV Preeminent.
SNC-Lavalin announced that it had reached financial close on the sale of its 100-per cent interest in AltaLink, Alberta's largest regulated energy transmission company, to Berkshire Hathaway Energy (Berkshire). This follows the receipt of regulatory approvals from the Alberta Utilities Commission and approvals pursuant to the Competition Act and Investment Canada Act. Based on the terms of the agreement, the transaction values AltaLink at approximately $7.2 billion and will result in gross proceeds to SNC-Lavalin of approximately $3.1 billion.