Arrests in absense of extradition?
<p>If country A and B has no extradition treaty, then can B arrest As citizens residing in B if A requests? </p>

<p>Sure they can arrest them.  Are you thinking you can go to a country yours has no extradition treaty with and just commit arbitrary crime sprees with impunity?  Presumably you mean to ask if they can extradite someone even without a treaty, and the answer is: depends on their laws, but otherwise of course they can if they feel like it (which may require giving them something in return).</p>

<p>An extradition treaty just creates a formalized process for handling extradition requests, which may include the types of crimes that may be considered, who can be considered or exempted, and the specific procedures a country may go through to decide on whether or not to grant the extradition. </p>

<p>The existence of a treaty does not guarantee the request will be granted.  US requests to extradite <a href="https://en.wikipedia.org/wiki/Roman_Polanski_sexual_abuse_case" rel="nofollow noreferrer">Roman Polanski</a> from Poland, France, and Switzerland have all failed, despite the fact that the <a href="https://en.wikipedia.org/wiki/Extradition_law_in_the_United_States#International_extradition" rel="nofollow noreferrer">US has extradition treaties with all of them</a>. Several countries, such as France and Canada, will also refuse to extradite anyone who may be subject to the death penalty. <a href="https://www.nytimes.com/2001/03/31/nyregion/france-will-not-extradite-if-death-penalty-is-possible.html" rel="nofollow noreferrer">This has gotten in the way of US extradition requests before</a>.</p>

<p>I interpret the question a bit differently, as asking can B harass an A citizen in their territotory by arresting them simply because A asked them to? If you are a citizen of A, you can be arrested in B for committing a crime in B. If you are a citizen of A and committed a crime in A (not B) but there is an extradition treaty, you could be arrested and extradited. If there is no crime in B and no possibility of extradition from B to A, then an arrest in B would essentially just be legal harassment. If a nation allows arbitrary arrests, then you could theoretically be arrested without cause. In those nations which require that arrests have some legal basis, you either have to have committed a crime within the jurisdiction, or there has to be a proper extradition request which purports that you committed one of a specified set of crimes in another jurisdiction, in the context of an extradition treaty.</p>

extradition