how to explain extradition

swimmingfrog

here is a sentence:

first, these governments began to reject what had been a primary intent of extradition, the expedite the return of political offenders, and instead sought to dissdents fleeing despotic regimes.

中文extradition的解释是: 将逃犯的审判权合法的让渡给另一个州,国家或政府..

在什么情况下才会发生这样的事,为什么自己国家的罪犯要让别的国家审判?尤其是文章中指的政治犯? 想知道一些背景知识