Trademark laws vary from country to country
As a result of the WTO (formerly GATT) Trade Related Intellectual Property ("TRIPS") agreement, trademark law globally is gradually becoming harmonised. This does not mean that trademarks registered in one jurisdiction automatically become registered in another jurisdiction (although a 'Community Trade Mark' system whereby a single registration with the OHIM registry can lead to a trade mark covering the 15 (soon 24) members of the European Union does exist), but it does mean that many trademark laws are shared by various countries. For example, Art 15 of the TRIPs agreement defines "sign". This definition or variations thereof can be found in a variety of countries' trademark legislation.
The Madrid Agreement allows trademarks registered in one country to be registered in other countries and territories.
Trademark laws of various countries: