Good piece by Professor Steve Peers on exclusion from refugee status in EU law: What if a refugee allegedly supports terrorism? The CJEU judgment in T. Click the link to read the full post. This gives you an idea of what issues arose:
This case concerned a Turkish national who moved to Germany back in 1989 and obtained refugee status there in 1993, on the basis of his activities in support of the PKK, the Kurdish group which Turkey (and subsequently also the EU) regards as a terrorist organisation. However, those links later led to a conviction for supporting terrorism, due to his collection of money for the PKK and distribution of PKK literature. His residence permit was revoked but he retained refugee status, and he was not expelled from the country. Nevertheless, he still challenged the revocation of his residence permit.