Royal commissions are advisory committees established by the government to investigate a matter of public concern on an ad-hoc basis.
The government may set up a royal commission if it wishes to be seen as addressing the investigation in a non-party political way.
A government is not bound to accept the advice of any royal commission.
Fewer royal commissions have been established in recent years.
In practice, royal commissions have sometimes been established to deal with issues that a government feels may be too controversial to be seen tackling itself.
The size of a royal commission, its chairperson, membership and remit are set by the government.
Most commissions take evidence, deliberate and then produce a final report.
The government usually outlines at the time of its establishment when it expects a royal commission to produce its final conclusions.
The average duration from establishment to report is between two and four years.
But certain royal commissions can have a semi-permanent existence.
For example, the Royal Commission on Historical Manuscripts was first set up in 1869 with the task of advising and assisting in the preservation of historical manuscripts and to publish them.
It is still in existence today.