In order to sketch the limitations of the system in more detail, though, it is obviously necessary to study its foundations. Justifying the limitations based on a utilitarian approach does not encounter much difficulty, but it would be rather difficult to justify limiting a right once defined as a natural right.
Considering patent rights as proprietary rights would presumably overcome some of the drawbacks of the utilitarian approach. However, it would make necessary a new effort in defining the whole system and a rearrangement of the position and nature of its limitations. This thesis looks particularly at Iranian law for its unique approach to considering the rights in question as proprietary rights: In Iran’s Patent and Trademark Act of 1931, this subject of protection was vaguely considered as "rights". Furthermore, "economic rights" are already a category in the Civil Code and the possibility of inserting IP rights into this category has since been debated. Finally in 2008 with the enactment of the new Patents, Industrial Designs and Trademarks Act, in which the legislature explicitly used the term "property" for these rights, the debate then shifted towards how to justify patent rights as proprietary rights, which are evidently also already categorized in the Civil Code. Thus, this study aims to clarify this aspect of the Iranian patent law as well.
According to the justifications based on natural-law theories, the main aim of the patent system is to protect the proprietary rights of the patent holders. Considering them as proprietary rights, however, should by no means imply that they are absolute and unlimited rights. Like the property system of tangible assets, which is subject to many external limitations, the IP system must also be limited.
In order to answer the research questions in this project, the hypothesis is that none of these limitations are internal to the patent system but are imposed externally i.e. by other branches and main policies of the whole legal system. Consequently, defenses can be divided into two categories: first, defenses related to the subjects outside patent protection and hence not considered as a limitation to the right, such as obviousness, lack of utility etc.; second, defenses which can be assumed as limitations to the right. These limitations are not inherent in the patent system but are imposed by other areas of the legal system. Thus, e.g. an experimental use defense can be considered as a limitation which is imposed by human rights principles; a misuse defense may in fact be imposed by competition law. In carrying out such analysis, the balance between the patentee's rights and the public interests are ensured by the main policies of the legal system, which need to be clearly defined and classified. In doing so, the study will further compare the laws and case law of the U.S. and Europe to the Iranian law in this respect.