To expand on whoevercares' comment, recently someone committed a crime in Taiwan and fled to Hong Kong. To close this loophole and prevent HK from becoming a safe haven for criminals, the Chief Executive of HK proposed a new law to facilitate extradition of these crime suspects from HK to various jurisdictions in the region, including Taiwan and mainland China.
Countries without extradition treaties can still extradite criminals on a case by case basis. It was also very cheeky of them to use a criminal from Taiwan R.O.C - a democratic nation with a strong rule of law - as an excuse for an extradition treaty with the Mainland Area of China, a communist dictatorship where laws are at the whims of party members.