Learn Dutch: Aangezien het bewijs ontbreekt, dient de jury hem onschuldig te verklaren. - Since the evidence is missing, the jury is obliged to declare him innocent.

Dienen te followed by an infinitive is a formal way to express an obligation, similar to 'to be obliged to' or 'ought to'. While you could use moet here, dient fits the formal, legal context of a jury. Note that unlike moeten, dienen always requires the word te before the infinitive at the end of the sentence (te verklaren).

Why is the word order dient de jury rather than de jury dient?

This is the classic V2 (verb-second) rule in action. The entire introductory clause Aangezien het bewijs ontbreekt counts as the first piece of information. The main clause must immediately follow it with the conjugated verb in the second position (dient), pushing the subject (de jury) into the third position.

Could I just use omdat instead of aangezien here?

Yes, you could use omdat (because), and the word order would stay exactly the same since both are subordinating conjunctions. However, aangezien (since / seeing as) sounds slightly more formal, which pairs perfectly with the formal tone of dienen te.

The verb is ontbreken (to lack / be missing). Why doesn't it split in this sentence?