Clause 3 deals with the duties and obligations of the Engineer and his assistants. Sub-Clause 3.1 deals with the role and duties of the Engineer. The Engineer is deemed to act for the Employer. The Engineer has no authority to relieve the Contractor of his duties, obligations or responsibilities under the Contract; nor can the Engineer amend the Contract. Under Sub-Clause 3.2 the Engineer can delegate authority to any assistants; however, the Engineer cannot delegate the responsibility to make Determinations. Under Sub-Clause 3.3 the Engineer may issue instructions or modified Drawings at any time, which are necessary for the execution of the Works. If the instruction constitutes a Variation, then it is dealt with under Clause 13 [Variations and Adjustments]. The Contractor is required to comply with any instruction given by the Engineer or delegated assistant. Sub-Clause 3.4 deals with the replacement of the Engineer. The Employer must not replace the Engineer with someone against whom the Contractor raises reasonable objection. Sub-Clause 3.5 deals with Determinations. When making a Determination the Engineer should consult with each of the Parties and, if agreement cannot be reached, make a fair determination in accordance with the Contract, taking due regard of all relevant circumstances. Both Parties are required to give effect to any Determination unless, or until, it is revised under Sub-Clause 20.1 [Claims, Disputes and Arbitration].