Patent grants are territorial in nature. Each country grants its own patents. Countries and regions differ significantly in terms of scope of patents granted, exemptions, examination systems, evidence required to challenge patents validity, susceptibility of system to political abuse. Thus, a thing as an international patent is not yet recognized, however, a number of international treaties establish some consistency and minimum standards. Many of the international treaties are calculated to afford some recognition of filing dates to patent application filed in one country. Inventors are permitted 12 months from the date of their filing in their home country to file the application abroad. Systems such as the Patent Cooperation Treaty (PCT) permit inventors a cost effective way to secure further delay as regards national stage filing as it is often called. At present there are a number of international treaties governing patents. However, the most worldwide of these is the WTO TRIPS Agreement. Countries not yet signatories to the said agreement aim at bringing their intellectual property laws into compliance with TRIPS. Nonetheless, the place of patent systems in international treaties is uncertain. Again, there are vague parts at the intersection of such treaties such as TRIPS and the Convention on Biological Diversity.