The first reference to an 18 month time period has been traced to a 1956 preliminary report by a patent law revision committee in the Netherlands. This report suggested that patent applications should be laid open to the public within 8 months after the initial searching had been completed. As the initial searching was expected to be completed at 18 months from filing, publication should have occurred at 26 (18+8) months from filing. The patent law committee also suggested that pre-grant publication practices of the Scandinavian countries and the Federal Republic of Germany be taken into consideration when deciding on the appropriate publication time period.
By the early 1960s, portions of the Dutch proposal appear to have been referenced by patent law review committees in the Scandinavia countries which make reference to an 18 month pre-grant publication period in the Netherlands (as opposed to the 18+8 month publication period that was actually proposed). Contemporaneous patent law reform discussions in Germany described the 18 month time period as an element of the "Swedish proposal". Subsequent Dutch examinations of Scandinavian and German domestic patent laws would then reveal what appeared to be a regional consensus to adopt an 18 month publication period.
Following these discussions, the Netherlands was the first country to formally adopt an 18 month mandatory publication period in 1964, but it would not be the last. The Netherlands actions were quickly followed, and 18 month mandatory publication periods were instituted by Denmark, Finland, Norway, Sweden and Germany in 1968 and by France in 1969. Therefore, by the end of 1969, an 18 month pre-grant publication period was the consensus standard of these seven European nations.
The international publication provision of the Patent Cooperation Treaty (PCT), Article 21, was also drafted in the late 1960s. The preliminary publication provision contained in the 1968 draft made no reference to an 18 month publication period; however, the 18 month mandatory publication period appears in the 1969 draft version. No information has been located as to why the 18 month term was incorporated into the 1969 draft. The 1969 version of Article 21 was adopted at the Washington Conference 1970 and therefore incorporated into the published version of the PCT.
As a result of its inclusion in the PCT, subsequent attempts by states to harmonize their domestic patent laws with international standards have resulted in the domestic adoption of the 18 month mandatory publication period. - FICPI newsletter