Introduction
This article is to acquaint you with some of the factors affecting which domains you can register safely; i.e., without violating any statutes or risking unpaid confiscation by others desiring to own your domain. The discussion to follow is somewhat USA-centric, so if you are not a US citizen you'll need to research the differences that may apply to your country of residence.
Trademark Law
In the US, this is a somewhat nebulous subject, impacted by a combination of federal intellectual property law in general, trademark law specifically, applicable case law, and ICANN practices. As a general rule, it is risky to register a second level domain name identical or "confusingly similar" to a phrase already trademarked. You can check for live, trademarked phrases at uspto.gov, which provides a powerful search feature to help you.
The mere fact that a phrase is trademarked does not automatically mean you are out of luck. For example, if the trademark is for a single real dictionary word, like "dog" or "cat," you may be able to challenge the trademark on "public domain" grounds. The same applies to commonly used phrases, like "time will tell". Unique phrases, like "Joe's Pro Bike Shop" will certainly lead to problems on your end.
Sometimes, even a specific trademarked phrase, or something very similar to it, may be safe as long as there is little chance of confusion with the trademarked business, and a low probability that your domain will siphon internet traffic away from the trademark owner's web site. An example might be a phrase that is used within a completely different business sector than that of the trademark owner, and there is no duplication of the trademark owner's unique styling of the phrase in his/her corporate logo. These decisions can be complex, and may require the advice of a competent intellectual property lawyer.
The Clinton era Lanham Act provides some guidance on the general topic of internet domain trademark law. It is not an all-encompassing law, as common law and state regulation also impact the subject. Section 43(a) of the Lanham Act (15 U.S.C. § 1125(a)) disallows "false or misleading description of fact, or false or misleading representation of fact in commerce, which is likely to cause confusion, or to cause mistake, or to deceive as to the affiliation, connection, or association of such person with another person, or as to the origin, sponsorship, or approval of his or her goods, services, or commercial activities by another person." As you can see, this somewhat clarifies the issue of what can and cannot be considered a safe harbor for domain registration. The mere duplication (or semi-duplication) of a trademarked name does not automatically lead to risk of confiscation. The potential harm to the trademark owner is factored into the analysis.
Another aspect of the Lanham Act is that it protects, to an extent, the right of an individual to how his or her own name is used, even if his/her name is not trademarked. For example, if you create a domain like "daveletterman.com" and use the domain to falsely imply that Dave Letterman is endorsing a product you are selling on the associated web site, you would be in violation of the Lanham Act. You run a lower risk if the associated web site is non-commercial (say, an informational site about the individual), as long as the material you present is factual. Lanham Act aside, you need to be very careful in general when the individual's name is trademarked (either as the name by itself, or as part of a phrase like "Dave Letterman Enterprises"). These cases have been litigated in the past, typically in favor of the plaintiff.
Domain Extensions
Each domain extension (like .com, .net, etc.) falls under the jurisdiction of the laws and customs of a particular country. The major generic extensions, like .com, .net, .org, and .info may be registered by anyone anywhere.
Many other extensions have what are called "nexus requirements." These are conditions the applicable jurisdiction and registration authorities impose in determining whether or not you are entitled to own a particular domain name (for reasons apart from trademark infringement). For example, the .us extension is limited to US citizens, US residents, and those operating businesses or organizations in the US.
Nexus requirements vary by extension. Some relate to citizenship, others relate to residency, yet others relate to whether or not you are operating a web site related to the second level domain name, etc. Some extensions involve multiple nexus requirements (e.g., residency and relevance of the second level domain name to site content). Australia (.com.au) has one of the strictest nexus requirements; you have to actually be running physical business operations in Australia that are related to the domain name.
Important country specific extensions that are safe for anyone to own, without any material nexus requirements, include .at (Austria), .be (Belgium), .ch (Switzerland), .co.nz (New Zealand), .co.uk (Great Britain), .de (Germany), .eu (European Community), .ph (Philippines), .ro (Romania), .ru (Russia), and .co.za (South Africa). By "material," I am referring to the fact that a small number of the above extensions have the requirement that your domain be held by a registered agent with a physical presence in the applicable area (the .eu extension is an example) if you are not a local citizen. Major domain registrars sometimes provide registered agent services at no charge when you register a new domain using their system. The domain registrar simply owns the domain for you beneficially; you retain full rights to use or sell the domain as you wish, just as with any other domain.
In Closing
Domain registration law can be complex, and is an evolving topic, both in terms of formal "black letter" requirements, as well as applicable case law. There will be situations where you are obviously within a safe harbor, and other times where it is equally obvious that you are at material risk of uncompensated confiscation. In gray areas, a well trained intellectual property attorney may be required to help you make the correct call.
