In any criminal law case, the defendant has a right to the prosecutor's evidence in a procedural period known as "discovery." Discovery is how defendants learn what the prosecution plans on using against them in their case, and usually starts immediately following your formal charges. However, defendants have access to certain files (citations, arrest records, dash cam footage, and others) prior to being charged in a procedure known as "informal discovery."
Seems simple enough—you ask the prosecution for evidence and they give it to you, right?
Not so much.
There are two basic types of evidence: Brady material (or relevant) evidence and everything else. Brady material is evidence that offers "significant aid" in support of the defendant's case or a lesser punishment. This includes exculpatory evidence, which is any evidence that shows that the defendant was incapable of committing the crime he or she is being charged with. This could include alibis, witnesses, video evidence, photos etc.
Brady materials also include things that simply weakens the prosecutor's narrative. For instance, if the prosecution offers their key witness against you a plea deal to testify, that weakens the credibility of the witness. That's now considered Brady evidence because it supports the defendant's case.
What makes Brady disclosure different from other forms of evidence is that the courts require the prosecutor's office to disclose it. All other forms of evidence must be requested to be retrieved, but defendants are automatically entitled to Brady material disclosure.
So If I'm Entitled to Evidence, Why Do I Need a Lawyer to Request It?
In a perfect world, the prosecution would abide by every rule and burden asked of it. However, it is far from a perfect world, and having a lawyer on your side helps ensure a fair trial.
It's possible for prosecutors to (both intentionally and unintentionally) withhold evidence from the defense. Prosecutors are ultimately responsible for the disclosure of Brady material or lack thereof in any given case—so even if they were unaware that exculpatory evidence was in their possession (say, a police investigator made a deal the assistant DA was unaware of), it's considered a Brady violation.
If the defendant is convicted, then the prosecution is found to have withheld evidence (even accidentally), the defendant is usually granted a new trial. However, identifying a Brady violation is something very few people can catch—unless they're highly familiar with criminal law. It's part of a defense lawyer's duty to recognize when a Brady violation takes place and to take action on it.
Here's another compelling reason you need a lawyer:
Evidence on its own rarely exonerates a defendant. A lot of evidence is ambiguous—it suggests rather than directs. Evidence only provides the pieces, the "dots" of the case. A good lawyer knows how to build alternative narratives using those dots, presenting a case for the defendant's innocence based on the evidence. Good lawyers know how to use the prosecution's evidence to destabilize the prosecutor's proposed story.
Remember, criminal law requires juries to convict "beyond a reasonable doubt." Having a lawyer makes it far more likely to introduce doubt into your case.
The Defense Lawyer Is Your Shield Against Misconduct
It's a lawyer's job to know what evidence helps you, how to make less-obvious evidence strengthen your case, and to know what must be protested or requested. They know what's inadmissible and how to keep it from ever seeing trial. They know when the prosecution has made a mistake (or overstepped their bounds) and how to prevent it from affecting the case. They also know the rules of the court and its procedures—things like knowing where to go and who to go to in order to get what you need as quickly as possible.
Lawyers know how to "play the game." If you're facing a professional player on the other team, doesn't it make sense to have a pro on your team too?
The charges a person faces are far from a game—they're high-stakes, and they determine the direction your life takes for the next few years (at minimum). But when it comes to understanding the rules and how to make them work in your favor? You'll need a lawyer for that.
