When do we use 'are' and when do we use 'is'?

are both these sentences correct?

The jury is going to deliver a lesser sentence.
The jury were spread throughout the court hall (were or was?)

Regards,
Amar

At the risk of being annoying, juries deliver verdicts and judges deliver sentences. But I think both your sentences are fine as regards is and are, although with the second I would probably, personally, write "The members of the jury were spread throughout...."