and causes a h*ll of a lot of problems
basically it is a criminal case but the witnesses may be in China and not that keen on coming for their free holiday in UK - and so is less personal evidence - by letter or video, hearsay evidence and non admissible
or do you allow the possibility of conviction of a serious offence on iffy evidence ?
and if you think THAT is a law-skool question which will never happen
then google Bonhoeffer (yes the nephew of that one)
or go here BAILLII org
and case search for Bonhoeffer and you get something like this:
Bonhoeffer, R (on the application of) v General Medical Council [2011] EWHC 1585 (Admin) (21 June 2011) (View without highlighting) [100%]
([2011] ACD 104, [2011] EWHC 1585 (Admin), [2011] Med LR 519, [2012] IRLR 37; From England and Wales High Court (Administrative Court) Decisions; 206 KB)
General Medical Council v Bonhoeffer [2012] EWHC 2078 (Admin) (28 June 2012) (View without highlighting) [33%]
([2012] EWHC 2078 (Admin); From England and Wales High Court (Administrative Court) Decisions; 7 KB
You will also find it discussed in Europe Tahrir and Albert I think
and at the end of it, you get a good idea why we dont allow most times indictments for crimes committed abroad -and the exceptions when we do, it is a complete dogs dinner
Buenchico gives one ref
the one they rely on in these cases is the Sexual Offences Act 2004 and allows prosecution for some foreign offences/acts after 2004.