Under the FIDIC Red and Yellow Books 1999 editions, the Engineer acts as the Employer ' s representative with authority delegated under the contract. When an instruction requires the Employer’s prior approval, it is primarily the Engineer’s responsibility to obtain that approval before issuing the instruction to the Contractor.

The Contractor is not contractually required to verify whether the Engineer has obtained the Employer’s approval. The Contractor is generally entitled to rely on the Engineer’s instructions as valid and binding unless there is clear evidence to the contrary.

This principle avoids placing an undue administrative burden on the Contractor and maintains the hierarchical contract administration structure, where the Engineer is the primary point of contact and decision-maker.