Section 12 of the National Road Traffic Act deals with this particular issue and states:
No person shall drive a motor vehicle on a public road—
(a) except under the authority and in accordance with the conditions of a licence issued to him or her in terms of this Chapter or of any document deemed to be a licence for the purposes of this Chapter; and
(b) unless he or she keeps such licence or document or any other prescribed authorisation with him or her in the vehicle.
From this it is clear that a motorist must ensure that he or she has their driving licence with them. However the section recognizes a document that is deemed to be a licence for the purposes of the Act. Based on this portion of the legislation it is necessary to understand the legal meaning of the word “deemed”.
The legal definition of deemed is “to accept a document or an event as conclusive of a certain status in the absence of evidence or facts which would normally be required to prove that status”
In addition, a certified copy can only be commissioned by a legally recognized Commissioner of Oaths whose is bound to act in accordance with the binding legislation (Justices of the Peace and Commissioner of Oaths Act, 16 of 1963). Furthermore a certified copy is deemed to be a true copy of the primary original document duly certified by the relevant authority.
Finally, there is nothing in the wording of the section that expressly states that only a driving licence will be accepted.
Based on the reasoning above, as well as a wide interpretation of the applicable laws, it is arguable that a correctly certified copy of your driving licence may be carried with you when driving.