A codefendant is a person or entity named alongside one or more other parties in the same legal case. In a criminal matter, codefendants appear on the same indictment because prosecutors believe they took part in the same offense. In a civil lawsuit, they are sued together because the plaintiff claims each of them contributed to the same harm. Courts group these parties into a single case to avoid duplicating testimony, conserve resources, and reduce the risk of inconsistent outcomes on the same set of facts.
What that label means for you depends heavily on which side of the “v.” you sit on and whether the case is criminal or civil. The strategic pressures are different, the money works differently, and the risks of being tied to someone else’s conduct are different. The sections below walk through what matters most.
Why Prosecutors and Plaintiffs Group Defendants Together
On the criminal side, Federal Rule of Criminal Procedure 8(b) lets prosecutors charge two or more defendants in a single indictment when they allegedly took part in the same act or a connected series of acts.1Legal Information Institute. Federal Rules of Criminal Procedure Rule 8 – Joinder of Offenses or Defendants Two federal statutes drive most codefendant indictments. The general conspiracy statute, 18 U.S.C. § 371, makes it a crime for two or more people to agree to commit a federal offense and then take at least one step toward carrying it out, with up to five years in prison even if the planned crime never happened.2Office of the Law Revision Counsel. 18 USC 371 – Conspiracy to Commit Offense or to Defraud United States The aiding and abetting statute, 18 U.S.C. § 2, treats anyone who helps, encourages, or causes someone to commit a federal crime as if they committed it personally.3Office of the Law Revision Counsel. 18 USC 2 – Principals Conspiracy punishes the agreement; aiding and abetting punishes participation in the actual crime.
Civil joinder works along similar lines. Federal Rule of Civil Procedure 20 lets a plaintiff sue multiple defendants together when the claims arise from the same event or series of events and share at least one common legal or factual question.4Legal Information Institute. Federal Rules of Civil Procedure Rule 20 – Permissive Joinder of Parties Plaintiffs often name every potentially responsible party upfront to make sure enough insurance or assets exist to cover a judgment. Employers also get pulled in through respondeat superior, which holds an employer responsible for an employee’s negligent acts committed within the scope of employment, even if the employer did nothing wrong personally.
The Risks of Being Tried With Someone Else
Sharing a trial can hurt you. A codefendant facing thin evidence can still be convicted because the jury heard overwhelming evidence against the person sitting beside them. Federal Rule of Criminal Procedure 14 lets a defendant ask the court to sever the trial when a joint proceeding would be unfairly prejudicial.5Legal Information Institute. Federal Rules of Criminal Procedure Rule 14 – Relief From Prejudicial Joinder Winning that motion is hard. In Zafiro v. United States, the Supreme Court said severance is appropriate only when a joint trial creates a serious risk of compromising a specific trial right or preventing the jury from reliably determining guilt. Judges typically rely on limiting instructions telling the jury to weigh each defendant’s evidence separately.
The Bruton Problem
Confessions create a specific trap. If one codefendant confessed to police and implicated the other, then refuses to testify at trial, the second defendant cannot cross-examine the person who pointed the finger. In Bruton v. United States, the Supreme Court held that admitting a non-testifying codefendant’s confession at a joint trial violates the Sixth Amendment’s Confrontation Clause, even with a limiting instruction.6Justia. Bruton v. United States, 391 US 123 (1968) Prosecutors who want to use such a confession must redact every reference to the other defendant, persuade the confessing defendant to take the stand, or accept separate trials. Courts scrutinize redactions closely to confirm the problem is actually fixed rather than papered over.
Cooperation and the Race to Deal
This is where codefendant cases become personal. Prosecutors routinely offer one defendant a reduced sentence in exchange for testimony against the others. Cooperation agreements require the cooperating defendant to answer all questions truthfully, produce documents, testify before grand juries and at trial, and disclose all assets tied to the criminal activity.7U.S. Department of Justice. Plea and Cooperation Agreement
The payoff can be substantial. Under USSG §5K1.1, the government can move for a sentence below the normal guideline range when the defendant provided “substantial assistance” in investigating or prosecuting others.8United States Sentencing Commission. Substantial Assistance Report For crimes with mandatory minimums, 18 U.S.C. § 3553(e) lets the court go below the statutory floor when the government files the motion.9Office of the Law Revision Counsel. 18 USC 3553 – Imposition of a Sentence Only the government can file these motions, which hands prosecutors enormous leverage.
The dynamics turn fast. Two codefendants who trusted each other before arrest can find themselves racing to cooperate first, since the earliest cooperator typically gets the best deal. If your codefendant is cooperating and you are not, you are usually looking at the harshest sentence available.
Why You Shouldn’t Share a Lawyer
Hiring one attorney for two codefendants looks cheaper and almost always ends badly. ABA Model Rule 1.7 identifies a conflict of interest whenever representing one client would be directly adverse to another, or when there is a significant risk that the lawyer’s duties to one client would limit representation of the other.10American Bar Association. Model Rules of Professional Conduct – Rule 1.7 Conflict of Interest Current Clients In codefendant cases that risk is almost always present. If one defendant’s best strategy is to blame the other, a shared attorney cannot do the job. Courts generally hold a hearing before allowing joint representation to confirm informed, written consent, and many judges refuse to permit it when a plea deal or cooperation is on the table.
Joint Defense Agreements
Codefendants with separate lawyers do not have to work alone. A joint defense agreement is a written arrangement letting separate attorneys share strategy, documents, and confidential information without waiving attorney-client privilege. These agreements set the rules: what can be shared, how it is stored, and what happens if one party later leaves. Courts treat these agreements differently across jurisdictions, which is why the written framework matters. Without one, sharing information between defense teams can waive privilege and hand prosecutors fresh ammunition.
Who Pays What in a Civil Case
When a jury finds multiple defendants liable, the next fight is over who writes the check. The answer depends on the jurisdiction. Roughly seven states apply pure joint and several liability, meaning the plaintiff can collect the entire judgment from any one defendant regardless of that defendant’s share of fault. About 29 states use a modified version that caps joint liability based on a defendant’s percentage of fault, and around 14 states have moved to pure several liability, where each defendant pays only their own share.
The practical impact is large. Under pure joint and several liability, a defendant found 10% at fault on a $1 million verdict can end up paying the full amount if the other defendants are broke. That defendant can then sue the others for reimbursement, but collecting from someone with no assets is a separate problem.
Cross-Claims Between Codefendants
Codefendants in civil cases often fight each other as well as the plaintiff. Federal Rule of Civil Procedure 13(g) lets a codefendant file a cross-claim against another codefendant, arguing that the co-party is actually responsible for the plaintiff’s harm.11Legal Information Institute. Federal Rules of Civil Procedure Rule 13 – Counterclaim and Crossclaim The cross-claim must arise from the same transaction or occurrence as the original lawsuit. The result is that codefendants become adversaries within the same case, each working to shrink their own share of liability.
Settlement Credits
When one codefendant settles before trial, the remaining defendants do not necessarily owe the full original amount. Under the pro tanto approach, any judgment against the remaining defendants is reduced by the dollar amount the settling defendant paid.12Legal Information Institute. Pro Tanto If the plaintiff settled with one defendant for $20,000 and later won a $76,000 judgment against the remaining defendant, that defendant owes $56,000. Some jurisdictions instead reduce the judgment by the settling defendant’s percentage of fault, which can produce very different numbers.
Why Codefendants Rarely Get the Same Sentence
Sharing a trial does not mean sharing a sentence. Federal sentencing guidelines adjust each person’s offense level based on their specific role. An organizer or leader of a criminal operation involving five or more people faces a four-level increase, while a manager or supervisor gets a three-level increase.13United States Sentencing Commission. USSG 3B1.1 – Aggravating Role At the other end, a minimal participant receives a four-level decrease and a minor participant gets a two-level decrease.14United States Sentencing Commission. 2025 Primer on Aggravating and Mitigating Role
Those adjustments can translate into years of difference in actual prison time. Judges also weigh criminal history, acceptance of responsibility, and whether the defendant cooperated with investigators. Two people convicted at the same trial for the same crime can walk away with very different outcomes.