Clause 13.1, known as the "Right to Vary," is a pivotal clause in the FIDIC Yellow Book 1999. It grants the Engineer the authority to instruct variations to the scope of the works under the contract. This clause is essential for both the Employer and the Contractor as it provides a structured mechanism for changes, thereby offering flexibility and adaptability in project execution. The clause ensures that any changes to the original scope of work are not arbitrary but follow a well-defined procedural pathway, making it particularly useful in complex, long-term projects where changes are almost inevitable.
