Everyone loves a good courtroom scene. We get lots of dramatic speeches and over-acting and Jack Nicholson reminding us that we can in no way handle the truth. But more than that, these scenes ultimately lead to Lady Justice being served. The bad guys go to jail.
Unfortunately, much of the time justice gets served only because a screenwriter twisted the law beyond recognition.
The Crime: Murder, Assault, Bootlegging, basically being a Mob Boss and Tax Evasion
The Ruling: Guilty Because Your Lawyer Says So
Kevin Costner's Eliot Ness is determined to break the stranglehold that Al Capone has on Prohibition-era Chicago. He assembles an elite team of "untouchable" (i.e. not actually corrupt) cops, and after a couple dozen people are killed, they arrest Capone for the capital crime of tax evasion, which today can get you made secretary of the treasury. But anyway.
Look, Kevin Costner!
When Ness discovers mid-trial that the jury has been bribed, he confronts the judge, who is also in Capone's pocket, and threatens to expose him if he doesn't do something. Instead of declaring a mistrial, the judge switches the entire jury with the jury from the trial next door, after the trial has already begun.
In a moment of panic, Capone's lawyer changes the plea to guilty, and the courtroom erupts as though all crime has just been wiped off the face of the Earth.
Hooray! We're safe forever!
Ever had to go in for jury duty? And the lengthy selection process? All that stuff happens for a reason. Juries are specially selected to avoid a conflict in the case being tried -- hell, Capone's second cousin could have been in the jury next door for all they knew. That's why a judge doesn't have the power to place a jury that the lawyers haven't selected or interviewed, let alone do so mid-trial.
But this point becomes moot minutes later, when, seeing that the evidence is stacked against them, Capone's lawyer switches his plea to guilty. The court erupts, cheering, while Capone punches out his lawyer and is then seen in the background being led off to jail screaming, "Is this justice?"
Well, no, actually.
This is Sean Connery.
The whole point of the scene seems to be that Capone's lawyer switches sides and pulls the rug out from under Capone. But in real life, a court can't accept a plea without a defendant's verbal consent, no matter what the lawyer suddenly announces.
"Oh, and that DUI I got charged with last week? He's pleading guilty to that, too."
The lawyer works for the accused, after all. Which means that instead of the court celebrating like they had all just won the lottery when they hear the guilty plea, Capone actually could have just fired his lawyer, had him killed (not necessarily in that order) and then stuck with his not-guilty plea and bribed the next jury, too.