The specific limitation applies to National Energy Board processes, as far as I can tell, in the legislation. Within the range of proposed assessment processes, one of them limits the definition of public participant to someone with a direct interest, which is something that has been in place and is highly controversial in Alberta. It's been proposed at the federal level at different times and rejected because it's simply unworkable as a standard.
On May 30th, 2012. See this statement in context.