Good vs. Bad AI Prompts for Criminal Defense Lawyers

Every wave of new technology brings both opportunity and risk for defense firms—and AI is no exception. Adoption continues to grow across the legal industry with 54% of attorneys now reporting AI use for tasks like discovery review, motion drafting, and more (Law360, 2025). As this number grows, AI’s mere use will no longer offer a competitive edge over prosecution. Both prosecution and defense will likely be using AI in the future, so the advantage won’t lie in who uses AI, but in who uses it skillfully.

That skill begins with the prompt—the instruction you give the tool to tell it what to do. A well-crafted prompt unlocks AI’s full potential: accelerating discovery review, turning mountains of media evidence into one searchable source of truth, and reducing workload for every member of your team. With AI operating at its full capacity, it can consistently improve results for your clients.

What Makes an AI Prompt “Good”?

The best test of an AI prompt is the result. A good prompt can create case-changing moments by:

• Summarizing transcripts with page-line citations. 
• Cutting hours or days off discovery review.
• Generating structured reports in minutes.
• Spotting contradictions across interviews or between testimony and reports.

Keep in mind: AI will always give you an answer, even if the prompt could be improved. Many attorneys turn away from AI entirely because they are understandably frustrated with generic results. In most cases, these frustrations can be remedied with improved prompts. 

How to Write a Good Prompt

Like assigning work to a new legal assistant, the AI won’t know what you need unless you tell it clearly. When building your prompt, start with these four things:

1. Define Your Role

“I’m a defense attorney preparing for trial.”

The needs of a defense attorney can be different from those of a prosecutor or a plaintiff’s attorney. Start your prompt by explaining who you are. This will fill in several blanks for the AI, empowering it to give you a response that is practically applicable to your work.

2. Clarify the Task

“Identify all statements where the witness mentions the weapon, and flag inconsistencies across their two interviews.”

As with all legal work, specificity is key when clarifying the task. Many beginners using AI tools will simply ask it to “analyze” a transcript. Notice in this prompt the instruction to “identify” and “flag inconsistencies”. AI tools are more than capable of identifying inconsistencies across interviews so you can successfully impeach a witness, but not if you don’t communicate that’s what you’re seeking. 

This will never replace an experienced attorney—but it can greatly increase their capacity and speed. 

3. Provide Case Context

“This is a robbery case. The defendant claims he wasn’t at the scene. The transcript is from the store clerk’s interview.”

Case details help the AI distinguish between helpful and irrelevant results. Without this context, it is left to guess who the defendant is. If you simply wrote "analyze the store clerk’s interview”, the AI may assume the store clerk is your client. 

4. Specify the Format

‍“Return the quotes as bullet points with timestamps and speaker names, and include a one-line relevance note for each.”

Again, just like with training a new member of your staff, you need to tell the AI what format you like best. This increases the likelihood that the AI’s output will be usable.

What Makes a Prompt “Bad”

Beginner-level prompts plague many law firms. Bad prompts tend to be:

1. Too Vague

“Tell me what’s important in this transcript.”

These return broad summaries with no real value. Important to whom? Any information you add will strengthen the response you get. Tell it you’re a criminal defense attorney and it will know that exculpatory moments will be of interest to you. 

2. Not Tied to Your Role

“Help me understand this.”

But why? Are you drafting a motion to dismiss? Preparing for a deposition? This prompt may lead to an explanation of a basic legal concept, or a profile on a witness. To get the most that these tools can provide for your clients, take your time to expand on this prompt. 

3. Context-free

“Analyze the witness.”

The AI can’t tell what analysis you need. If you don’t tell it what matters, it will be left to guess. Is it supposed to tell you what the witness might look like? If they were in a good mood? You need actionable, case-altering insights—the AI can get that for you, but only if you ask. 

4. Formatless

“Summarize this call.”

You’ll likely get a wall of text instead of usable output. Try uploading a sample of the format or explaining that you’d like a spreadsheet—it can do that for you.

In each case, the problem isn’t the AI’s capability—it’s the lack of clear instruction. Better prompts lead to better results.

Prompt Examples: Bad vs. Good

Over time, you’ll learn to spot a bad prompt. Experimenting is key. It’s often surprising how much a small change can improve an AI’s output. Whereas a simple prompt may only tell you the duration of a jail call, a well-crafted prompt may surface details that the prosecution is hoping slip through the cracks. Countless local D.A.’s are already using AI tools in their work—it’s vital to learn how to do the same. 

1. Parsing Through a Deposition

‍Bad: “Summarize what the witness said.”

Too broad. Lacks task focus, legal context, and formatting.

‍Good: “As a defense attorney preparing a motion to suppress, review this transcript of the officer’s testimony and identify any timeline inconsistencies regarding the search and seizure. Provide direct quotes, timestamps, and explain how they contradict the arrest report.”

This prompt tells the AI who you are, what you want, and why it matters.

2. Reviewing Jail Calls

‍Bad: “Tell me if anything important is in this call.”

Too vague. “Important” could mean anything. There’s no guidance on what to look for, who’s asking, or how the results should be presented.

‍Good: “As a public defender reviewing discovery, analyze this 30-minute jail call for any statements related to bail, contact with co-defendants, or admissions about the alleged incident. Flag each with direct quotes and timestamps.”

This prompt gives the AI direction, sets legal relevance, and requests a structured output. It helps you scan for red flags without listening to the entire call yourself—saving time and surfacing high-impact details quickly.

3. Building a Case Timeline

‍Bad: “Give me a summary of the events.”

Too vague. There’s no instruction on what kind of events matter, how to organize them, or what legal purpose the summary should serve.

‍Good: “As an investigator preparing a timeline for trial, extract every mention of a date, time, or sequence of events from this transcript. Organize them chronologically and include a timestamp and speaker for each quote.”

This prompt tells the AI what kind of data to pull, how to structure it, and what role it's supporting—making the output immediately useful for timeline exhibits, motions, or strategy sessions.

‍Owning a tool doesn’t mean you’re using it well. Most firms will adopt AI—but few will master it. In a field like criminal defense, where the smallest detail can flip a case, that difference is huge. Mastery means knowing how to guide the tool with precision, especially when the stakes are high. From flagging Miranda violations to building a case timeline or spotting inconsistencies across interviews, the strength of your prompt directly affects the strength of the result.

Use Rev to Unlock Your Edge

Rev is built for criminal defense. There’s no room for error or privacy issues in criminal defense—and unlike generic AI tools, Rev understands what’s at stake. 

Our tools are made specifically for you. Rev delivers court-ready transcription and AI tools tailored for defense teams. Our tools are always secure and SOC 2 Type II compliant.

Instead of digging through hours of jail calls or body cam footage, Rev helps you surface the one moment that changes everything—fast. With secure, searchable transcripts and legal-specific AI templates, you can prepare stronger cases and get to the truth faster.

Your clients deserve a defense team with every advantage. Try Rev today.