Verification is the testing of an individual measuring device or a random sample of measuring devices for compliance with legally defined requirements by a verification authority. Measuring devices can only be calibrated if they meet the essential requirements in terms of measurement technology and quality. These are regulated in the Measurement and Verification Ordinance. If the measuring device complies with the requirements during the verification test, an official marking for a further verification period indicates that the device may be used for commercial or official purposes and for measurements in the public interest.

In Germany, the national measuring service for the verification of measuring instruments is formed by the verification authorities of the 16 federal states and the testing laboratories recognized by them. The verification authorities test measuring instruments

• of trade: e.g. scales, petrol pumps at filling stations, tankers for mineral oil, fare indicators in cabs,
• occupational safety and environmental protection: e.g. audiometers, exhaust gas measuring devices and
• the police: e.g. breath alcohol measuring devices, radar measuring devices

The state-approved test centers test utility meters such as electricity meters, gas meters, water meters and heat meters. Over 120 different types of meters are subject to mandatory verification. The details are set out in the Measurement and Verification Ordinance. There are different legally prescribed calibration validity periods for the different types of measuring devices, which are regulated in the Measurement and Calibration Ordinance (see Appendix 7).