R.A. 4566 as amended by P.D. No. 1746 provides that no contractor (including sub-contractor and specialty contractor) shall engage in the business of contracting without first having secured a PCAB license to conduct business. It is an offense to engage in contracting business without a license first being obtained. All architects and engineers preparing plans and specifications for work to be contracted in the Philippines shall stipulate in their invitation to bidders, whether a resident of the Philippines or not, and in their specifications that it will be necessary for any bidder, whether contractor, sub-contractor or specialty contractor, to have a license before his bid is considered. The purpose of the Contractors License Law (R.A. 4566) is to ensure, for the safety of the public, that only qualified and reliable contractors are allowed to undertake construction in the country. The law also aims to promote for the benefit of the public and private sectors and for the national interest, the orderly growth of the contracting sector and the upgrading of construction capability.