When did someone fail to bring up info that completely blew their case in court?

The opposing counsel asked,

Isn't it true that you hit the victim in the face with a brick?

The client said,

That Marcus hit him with the brick, I hit him in the back with a piece of wood.

A friend of mine's case is a public defender.

A girl was busted on possession charges and told him she didn't

have any on her when they arrested her. He thought, okay, we'll use that. Turns out she didn't

have any on her when they arrested her because she'd just sold it all to an undercover cop.

This particular specimen had sent a photo of his victim's beaten face to them with a message saying

something along the lines of

do you want this to happen again? He came across very well in court up to that point, but his mask

slipped when that evidence came out. Oh, one custody case, the client failed to tell me he was

previously convicted of all sorts of awful things against his family in the past.

Lawyer in the UK. I acted for a member of a famous prevert hunting group. My client was charged

with various offences relating to his vigilanteism, most seriously, causing grievous bodily

harm with intent. He wanted me to fight the case on a public interest defence point that isn't available to him

in statute or at common law contrary to my advice. I followed his instructions, as I'm bound to do.

If the state won't punish the creeps properly, then it's left a men like my client to take the law

into their own hands, which I knew was a horse crap argument for a whole host of reasons. His laptop was

seized by the police and submitted for forensic examination. He had a staggeringly huge database

of incriminating material on it. He himself, as it turns out, was the worst case example of the

...