Australia`s Constitution allows the executive government to enter into contracts, but it is customary for contracts to be presented in both houses of Parliament at least 15 days before signing. Treaties are considered a source of Australian law, but sometimes require the adoption of a parliamentary act based on their nature. Contracts are managed and maintained by the Department of Foreign Affairs and Trade, which stated that the “general position under Australian law is that contracts to which Australia has joined, with the exception of those that end a state of war, are not directly and automatically included in Australian law. Signing and ratification do not allow treaties to operate on national territory. In the absence of legislation, contracts cannot impose obligations on individuals or create rights in national law. Yet international law, including contract law, is a legitimate and important influence on the development of the common law and can be used in the interpretation of laws.  Treaties can be implemented by executive measures and existing laws are often sufficient to ensure compliance with a treaty. IpPC is a contract to prevent the introduction and spread of pests to plants and plant products and currently has 177 government recipients. IPPC has developed plant health guidelines and serves as a reporting centre and source of information. Seven regional plant protection organizations have been established under the aegis of ipPC. For example, the North American Plant Protection Organization (NAPPO) consists of the United States, Canada and Mexico, which participate through APHIS, the Canadian Food Inspection Agency (CFIA) and the Plant Health Directorate. The European and Mediterranean Organization for the Protection of Plants (EPPO) is an intergovernmental organisation that is also responsible, within the framework of the IPPC, for plant health cooperation between 50 countries in the European and Mediterranean region. In India, the themes are divided into three lists: the Union, the State and the Simultaneous. In the normal legislative process, issues on the trade union list must be regulated by law by the Indian parliament.
For the subjects on the national list, only the state legislator can legislate. Both governments can legislate on subjects on the same list. However, for the implementation of international treaties, Parliament can legislate on any subject and even repeal the general distribution of lists of subjects. A party`s consent to a contract is void if it has been issued by an agent or entity without the power to do so in accordance with the national laws of that state. States are reluctant to investigate the internal affairs and processes of other states and, therefore, a “clear violation” is necessary, so it “would be objectively obvious to any state dealing with the issue.” At the international level, there is a strong presumption that a head of state has acted within his own authority.