The need for fuel sampling is covered by Article 6.6 of the F1 technical regulations, which reads:
6.6 Fuel draining and sampling
→ 6.6.1 Competitors must provide a means of removing all fuel from the car.
→ 6.6.2 Competitors must ensure that a one litre sample of fuel may be taken from the car at any time during the Event. Except in cases of force majeure (accepted as such by the stewards of the meeting), if a sample of fuel is required after a practice session the car concerned must have first been driven back to the pits under its own power.
→ 6.6.3 All cars must be fitted with a -2 ‘Symetrics’ male fitting in order to facilitate fuel sampling. If an electric pump on board the car cannot be used to remove the fuel an externally connected one may be used provided it is evident that a representative fuel sample is being taken. If an external pump is used it must be possible to connect the FIA sampling hose to it and any hose between the car and pump must be -3 in diameter and not exceed 2m in length. Details of the fuel sampling hose may be found in the Appendix to these regulations.
→ 6.6.4 The sampling procedure must not necessitate starting the engine or the removal of bodywork (other than the cover over any refuelling connector).