modality - 'If he is convicted, he would be taken' - Mixed conditional?

Consider:

If he is convicted, he would be taken to a lawful place of execution where he’d be put down in the most humane method known to science, either by hanging or by lethal injection.

Is the following some kind of mixed conditional? Why is "would" instead of "will" or "should" used in the second clause?

Answer

To begin with, forget that rubbish about "1st, 2nd, 3rd, 0, mixed conditionals". These terms do not name anything which actually exists in English; they're merely a pedagogic device for introducing learners to a small number of conditional constructions. They're what I call "baby rules": rules you give beginners to tide them over until they know enough to break them. You're a grown-up now, and all these n-conditionals can do is confuse you. Throw them away.

In formal terms you are quite right; a realis ('indicative') in the protasis (*IF clause, condition clause) ordinarily demands a realis in the apodosis (THEN clause, consequence clause), and an irrealis ('subjunctive') demands an irrealis:

If he is convicted, he will be taken . . .
If he were convicted, he would be taken . . .

However, your example is not a formal, written utterance but quoted speech; and the use of modals in speech has been in transition for at least a century now. The line between realis and irrealis has become blurred: the past forms (could, might, should, would) have become largely divorced from what are conventionally regarded as their present forms (can, may, shall, will) and have taken on present-tense meanings which are not necessarily or entirely irrealis.

And this little passage addresses a situation where the line between realis and irrealis is inherently ambiguous. Rupert is employing a hypothetical but very actualizable situation to describe what he sees as very real, non-hypothetical differences between his own sense of justice and what he believes to be Omar Bakri's sense; it's not surprising that he wavers between realis and irrealis forms.

You'll encounter this sort of thing frequently. You don't want to emulate it; but you shouldn't be particularly troubled by it, either.