At a meeting held in Paris on 14 October 1999, the directors of the national metrology institutes (NMIs) of thirty-eight Member States of the BIPM and representatives of two international organizations signed a Mutual Recognition Arrangement (CIPM MRA
) for national measurement standards and for calibration and measurement certificates issued by NMIs. A number of other institutes have signed since then.
National metrology institutes have been collaborating and carrying out international comparisons of their national measurement standards for more than one hundred years. However, the ad hoc recognition that has resulted is now not considered to be sufficient, hence the move towards the MRA.
The CIPM MRA was initiated by Resolution 2 of the 20th CGPM in 1995, which called for increased cooperation between the NMIs, the regional metrology organizations and the BIPM to improve worldwide traceability of measurement standards. Discussions with the International Laboratory Accreditation Cooperation (ILAC) reinforced this view as to the need for a more formal recognition of national measurement standards.
During 1996 discussions took place among the regional metrology organizations related to the possibility of drawing up regional mutual recognition agreements. These stimulated a BIPM draft of a worldwide agreement that was presented at a meeting of directors of the NMIs held in Sèvres in February 1997. The overall favourable reception to this initiative led to a second draft being developed during the year that followed. This was presented at the following meeting in February 1998 and initialled by the directors of thirty-nine NMIs. Further discussions then took place and in August 1999 agreement was reached on the final text that was signed on 14 October 1999. The meeting of directors on 14 October took place at the Collège de France during the week of the 21st CGPM and the signature of the MRA was formally welcomed by the delegates of the governments of the thirty-six Member States present in Resolution 2 of the 21st CGPM, adopted on 15 October.
At its 92nd meeting, in October 2003, the CIPM approved minor modifications to the Technical Supplement concerning the execution of supplementary comparisons and their subsequent impact on CMCs published in Appendix C.