How to use "defence" in a sentence

In reality, however, all he does is press 'play' on the recording device and write down a few notes about when the judge enters, when the prosecution or defence speaks, or what the final verdict is

The defence says that this is not murder, but manslaughter

They say this is the case because Miss Lee was not in a sane state of mind when she killed Mr Dawson; they say that this crime was in defence of her sister