It is a fundamental principle of contract law, one which public policy favours and subject only to certain well-established and narrowly defined exceptions, that parties are free to determine for themselves the terms of contracts voluntarily entered into. Regrettably, the Supreme Court of Canada recently departed from this principle in Tercon Contractors Ltd. v. British Columbia (Transportation and Highways), thereby injecting uncertainty into the enforceability of contractual arrangements. Published in the August 2010 issue of Canadian Lawyer as part of Bryan Haynes' regular column.