Regulation in the field of the investor activity expresses all types of state's intervention by the mechanisms and the means that affect the investor's conduct in directing his investment activity which are designed to achieve the public interest, and includes imposing restrictions on the regulated activity, and guarantees to encourage this activity as well. However, the recognition of the sovereign right of the state to regulate the activity of the investor is what encircles it with a set of rights and duties, the most important of which is its commitment to the balance between the principles that guarantee the rights and freedoms of the investor, and the constitutional principles that guarantee the protection of the public interest, and in the process of this regulation it bears the responsibility to achieve the balance that guarantees the protection to both the rights of the investor and the public interest. And that the conflict that may arise between the state's exercise of its authority in the regulatory field for achieving the public interest and the impact of the investor's rights and the stability of his/her investment project is what necessitates the search for means that set the balance to stabilitate the various interests in determining and balancing the public interests that appear in the state's intervention to protect the public interest and the private interests that appear in the interests of the individuals affected by this intervention, who are the investors in the field of this study. The importance of this study revolves around dealing with the limits of the state's exercise of its authority in regulating in order to achieve the public interest as the ultimate goal pursued by each state according to the authority available to it in issuing legislations regulating investment, as well as stating the content of this public interest in the regulatory activities related to the investor, and the means that it resorts to in order to achieve its public interests, some of which meet the interests of the investor and support the protection of his/her investment, and others that may conflict with his/her interests, and determining the means that achieve the balance between the state's exercise of this authority and the protection of the investor's rights, whether those related to the contractual relations to which the state is a party with the investor, by stating the conditions that can be included in these contracts and studying their effectiveness in achieving this balance, and the consequences of violating them. The theoretical importance of the study also appears in identifying the means the law establishes and are applied within the framework of contractual relations or other relations in light of the absence of the investor connection with the state by a contract.