Most people seeking asylum who came by boat are refugees. According to the Australian Parliamentary Library, between 70-100% have typically been found to be refugees. In 2012-13, 88% of those who came by boat were found to be refugees.
People seeking asylum go through strict processes before they are allowed to stay. They are detained when they first come. They must pass identity, health and security checks before they can be released into the community. They go through a strict process of determining whether they are a refugee. If they are found to be refugees, they must pass more security, health and character checks before they get to stay. It is therefore very unlikely that a criminal or terrorist would choose such a difficult and dangerous method to come to Australia.
If people have committed war crimes, crimes against peace, crimes against humanity or other serious non-political crimes, they cannot be refugees under the definition in the Refugee Convention .