Many people think that something patented in one country is automatically patented world-wide. Patents usually don't work that way. Here's how it works for almost all US patents (the ones we specialize in).
Imagine you're an inventor who comes up with a new (patentable) idea, say, a new way to make solar cells. After careful research, you determine that you're the first person to do this. You file for (and receive) a patent for your invention from the United States Patent and Trademark Office.
Congratulations! You now have the right to stop other people from making, using, selling, offering for sale, or importing your invention in the US for 20 years. Only in the US — it's a US patent. You cannot stop anyone from using your patent outside of the US. To get that right in another country, you must apply for a patent in that country, usually within one year of receiving a US patent.
Almost all US patent-holders decide not to do this, usually because they plan to use their patents only in the US. Once they make that decision, those patents can be used anywhere else in the world, for free.
As you can imagine, there are many potential complications to this process. Our basic explanation applies to almost all US patents, however. For more information, please consult the website of the Office of the Administrator for External Affairs of the United States Patent and Trademark Office here.
OK, it's legal. But isn't it wrong to use ideas this way?
It sounds like stealing, doesn't it? You come up with a great idea, go to a lot of work and expense to patent it (in the US), and then I just take what you've done, without asking, and get rich off it. That sounds unfair. Except that most companies choose not to file in most countries, which means that they essentially dedicate the invention to the public in those countries where they do not file. Most often, this choice is related to the business and markets that they company values. Most emerging markets simply have not been deemed important enough for companies to elect (and hire local attorneys, and pay the governments there) to obtain patents there.
The US government (and all governments that have signed the 1994 Agreement on Trade Related Aspects of Intellectual Property Rights) agrees to give patents to people who invent things on the condition that the inventor publishes all the relevant information needed to make the invention work – and pay the government and follow the rules required for obtaining a patent, which is a legal right granted by a country. If you don't comply, you can't get a patent. And this process must be done in each and every country (or regional group) in order to enjoy the exclusive rights that patents provide.