[The Real Slim Shady]

The lawyers are supposed to substantiate their case on why he is legally/morally right or legally/morally wrong.

There is only legal and illegal. Morals are not justification for murder.

No one really cares what the best metaphor for you all here is really.

I'm not asking for the best metaphor. I am asking for an accurate metaphor.

For the record, you do choose your lawyer both before and after you enter the courtroom.

For the record, you do not choose your lawyer after you enter the courtroom.

The lawyer does have his own opinion and chooses his own side, he can reject taking the case, but that is irrelevant to the topic.

As defence the lawyer can choose not to take a case. but he's not deciding his position in the courtroom.