Which countries have no extradition treaties with the United States?
Canada (Canada maintains an extradition treaty with the caveat that any persons extradited will not be subject to the death penalty. The Conservative government under Stephen Harper reversed this position, but the Supreme Court of Canada has placed this reversal in a state of legal uncertainty.)
Central African Republic
Sao Tome e Principe
United Arab Emirates
Extradition treaties exist to speed up extradition by having the ground rules already agreed upon and the infrastructure and logistics to support prisoner transfers and transport between countries.
That means in a country with an extradition treaty a person can be retrieved from that country in a timely manner at the request of government officials.
This has led to the mistaken belief that you can not be extradited from countries that do not have extradition treaties already in place. This could not be further from the truth. The reality is that the US can request extradition through diplomatic contacts from any country even if no treaty already exists.
Whether or not that country bothers to comply with the request is an entirely case by case basis. However many countries without extradition treaties are more than happy to comply with a request if the circumstances are favorable for them to gain some favor, money or sometimes just good press.
Another risk of being in a non extradition country is that upon receiving a request to extradite you, without a treaty to follow, they may simply lock you up in local prisons for years while they investigate the claim. This can cause years of additional incarceration (whether or not you are guilty) in addition to any sentence that may be given upon return to the US.
A country without an extradition treaty in place simply means
you are at the mercy of that country and its decisions rather than
there being laws already in place to deal with the extradition
request. It does not mean you wont be extradited, it just means you
may spend years dealing with them while they figure out if they
will extradite you, or not.
With WHAT other countries