The traditional purpose of a privative clause is to prevent any appeal.
However, privative clauses of recent vintage are carefully drafted to prevent not only appeals but judicial review (such as certiorari).
In Eggertson v ATA, a judge of the Alberta Court of Queens Bench adopted these words;
"A privative clause is a statutory provision which purports to exclude the jurisdiction of a superior court to review the legality of actions taken by a statutory body. Where there is a 'full' privative clause, that is one which declares that decisions of the tribunal are final and conclusive, and from which no appeals lies and all forms of judicial review are excluded, the courts will generally grant a high degree of deference to the tribunal."
The presence of a privative clause will significantly affect a litigant's ability to apply for a judicial review of a tribunal's decision and in the day-to-day issues arising from too-frequent sloppiness or errors in the findings of a tribunal, little solace can be taken from the 2008 words of the Supreme Court of Canada in Dunsmuir:
"The legislative branch of government cannot remove the judiciary’s power to review actions and decisions of administrative bodies for compliance with the constitutional capacities of the government. Even a privative clause, which provides a strong indication of legislative intent, cannot be determinative in this respect."
At the least, a privative clause obliges a reviewing court to show "deference" to the decision being reviewed, which means that a litigant would have to show that the decision was not reasonable. In practice, this is a virtual glass ceiling. Thus, the true impact of a privative clause.
In any event, most litigants would reasonably assume that they can go no further given, for example this wording in regards to the judicial review of a decision of the British Columbia Labour Relations Board:
"A decision or order of the board under this Code, a collective agreement or the regulations on a matter in respect of which the board has jurisdiction is final and conclusive and is not open to question or review in a court on any grounds."
In other common law jurisdictions, such as England, such clauses are called protective or preclusive clauses.
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