Such applications may be filed within one year of the earliest priority date and can claim the priority date of the or each earlier application. This means that any disclosure of the invention between the priority date and the filing of such further applications will not damage the novelty or inventive step of such further applications. This one year period, often referred to as the convention or priority year, therefore gives a breathing space in which to make further developments and to consider whether foreign protection will be required.
In practice, about 10 months is available for these purposes because the patent agent will need a reasonable amount of time in which to prepare foreign applications if this is required.

All countries of any reasonable commercial interest have patent law and it is possible to file patent applications in each individual country where you wish to have protection. However, this is an expensive procedure and there are two systems which help to reduce or delay costs in the patenting procedure.

The first of these procedures is governed by the European Patent Convention (EPC) and allows a single European patent application to be filed in respect of any combination of the following countries.
Austria, Belgium, Switzerland (including Liechtenstein), Germany, Denmark, Spain, Finland, France, Britain, Greece, Ireland, Italy, Luxembourg, Monaco, Netherlands, Portugal and Sweden. A European patent may also be extended to Albania, Lithuania, Latvia, Romania and Slovenia.
Although the cost of filing a European patent application is much greater than that of filing an application in any one of these countries, it is cheaper than filing several such applications. The break-even point is generally considered to be between two and three countries.

A European patent application allows a single application to be prosecuted and the procedure is similar to the British procedure described above until a European patent is granted. Once this happens, the European patent has to be converted into individual national patents in each of the states where you still wish to have protection. Needless to say, this procedure can be rather expensive because of the translation costs and local registration fees which are involved. It does allow a decision on where you wish to have protection to be postponed and still generally represents better value for money if three or more countries are required. Also, the relatively heavy national registration costs are incurred once a patent application has successfully passed through the European Patent Office examination procedure so that you are more certain of obtaining useful protection.

The other arrangement for reducing the number of applications is governed by the Patent Cooperation Treaty. This allows a single PCT application to be filed and covers the following countries.
Albania, Armenia, Australia, Austria, Asabajan, Barbados, Bellarus, Belgium, Benin, Bosnia and Herzegovina, Brazil, Bulgaria, Burkina, Faso, Cameroon, Canada, Central African Republic, Chad, China, Congo, Côte d’Ivoire, Croatia, Cuba, Cyprus, Czech Republic, Democratic People’s Republic of Korea, Denmark, Estonia, Finland, France, Gabon, Gambia, Georgia, Germany, Ghana, Greece, Guinea, Guinea-Bissau, Hungary, Iceland, Indonesia, Ireland, Israel, Italy, Japan, Kazakhstan, Kenya, Kyrgyzstan, Latvia, Lesotho, Liberia, Liechtenstein, Lithuania, Luxembourg, Madagascar, Malawi, Mali, Mauritania, Mexico, Monaco, Mongolia, Netherlands, New Zealand, Nigeria, Norway, Poland, Portugal, Republic of Korea, Republic of Moldavia, Romania, Russian Federation, St Lucia, Senegal, Sierra Leone, Singapore, Slovakia, Slovenia, Spain, Sri Lanka, Sudan, Swaziland, Sweden, Switzerland, Tajikistan, The Former Yugoslav Republic of Macedonia, Togo, Trinidad and Tobago, Turkey, Turkmenistan, Uganda, Ukraine, United Kingdom, United States of America, Uzbekistan, Vietnam, Yugoslavia and Zimbabwe. Also, a European patent designating any combination of the EPC states may be covered as a single application in a PCT application.

A PCT application does not go as far as a European application in that it does not lead to grant of a patent. Instead, the “international phase” ends after a substantive examination report has been issued, to which it is possible but not necessary to file a response. The international phase ends 30 months after the earliest priority date of the application at which time it is necessary to convert the PCT application into individual national applications in all of the countries, including a European application, in which you wish to have protection.

A PCT application has advantages and disadvantages. The advantages include delaying considerable expense until the start of the national phase (30 months from priority date) and the issue of a search report before incurring these costs. The main disadvantage is that the total cost will be significantly higher than filing the individual applications within the convention year without using the PCT route. Another possible disadvantage is that grant of patents will be delayed somewhat because of the PCT procedure.

US patent law differs in several important respects from virtually all other countries. For instance, in most countries, the first to file a patent application i.e. the earliest priority date, is entitled to the patent protection. However, in USA, it is the first to invent. Thus, earlier priority may be given to an applicant who can show an earlier invention date, which will be before the earliest priority date. It is therefore important to keep all note books, lab records and the like relating to research and development work so as to provide evidence, should it be necessary, of an earlier date of invention. All work should be recorded in ink and dated and should preferably be signed by the researcher and even countersigned by his supervisor.

Where there is no obligation to draw to the attention of most Patent Offices any prior art of which you are aware or become aware before a patent is granted, the reverse is the case for US patent applications. There is a “duty of candour” on everyone involved in a US patent application from the inventor to the patent attorney to bring to the attention of the US Patent Office any prior art of which you are aware or become aware and which might be relevant to patentability. Failure to meet this duty will normally result in complete loss of patent rights in USA.

In order to keep patents (and some applications) alive, it is necessary to pay renewal or maintenance fees when the patent is granted and possibly while it is a pending application. These are generally payable annually and failure to pay results in loss of the patent or application.

The term of protection given by a patent varies somewhat in different countries but the typical period is 20 years from the date of the application.