According to section 11(1), the effect of the grant of a patent is that persons other than the owner of the patent may not exploit the patented invention in the country, unless the owner agrees to such exploitation.
Section 11(2) lists those acts the performance of which requires the agreement of the owner.
Subsection 3 deals with the right to institute proceedings against any person exploiting the patented invention in the country without the owner's agreement and is the owner's most important right, since it permits him to derive the material benefits to which he is entitled as a reward for his intellectual effort and work, and as compensation for the expenses which his research and experimentation leading to the invention have entailed. The performance of any act of exploitation falling within the scope of protection of the patent by a person, without the agreement of the owner, constitutes an infringement of the patent under subsection (3), subject to the exceptions provided in subsection 4 and Section 12.
Subsection (4): The first limitation contained in this subsection is usually called the "exhaustion" of patent rights. Under that principle, once a patent protected article (a patented product or a product made by a patented process) has been lawfully put on the market, the patent owner's rights in respect of that product are exhausted. This limitation assures free circulation of products in the country. The second limitation is aimed at avoiding a situation in which the exercise of the exclusive right might be prejudicial to the public interest in maintaining free movement of aircraft, etc. The paragraph itself is limited in four ways. First, it is only the "use" of the article that cannot be affected by the patent rights (i.e., manufacture or sale would be affected). Secondly, only that use which is exclusively for the needs of the aircraft, land vehicle or vessel is concerned. Thirdly, only aircraft, etc. of other countries are concerned and, fourthly, only those aircraft, land vehicles or vessels which temporarily or accidentally enter the airspace, territory or waters of the country are concerned. The third limitation concerns acts done only for experimental purposes, which implies that such acts must be for non-commercial purposes. The fourth limitation recognizes the so-called "prior user's" right. This right is established by "good faith" prior use or serious preparations for such use, within the territory of Antigua and Barbuda. The right does not extend to use which is different in nature (e.g. making a patented product as opposed to importing the product) or purpose (e.g. making the patented product on contract for another enterprise or for sale in general as opposed to making it for the internal use of the enterprise) from the actual prior use or, in the case of preparations, envisaged prior use. The right is further limited by paragraph (b). Paragraph (b) restricts the transferability of the right of the prior user to those circumstances in which a transferee (assignee, heir, etc.) acquires also the enterprise or business, or that part of the enterprise or business, in which the prior use or preparations for use occurred.