Say that a person is accused of committing a crime, they either hire a lawyer or have one appointed to them. Some time later, the lawyer learns that their client most certainly committed the crime. Perhaps the client shows the lawyer a video of them committing the crime (and it is proven to be genuine).

What does a lawyer do in this case? Are they required to continue to defend their client (and would that mean they may be forced to commit perjury?) or are they allowed to choose not to continue to represent their client in the interest of finding the truth and upholding justice?

If there are any historical cases where this sort of thing happened, mentioning them would be a plus.

For the sake of argument, let's assume that the lawyer is somehow able to know with 100% certainty that their client committed the crime, so there is no issue of the lawyer passing judgement when there is a chance of doubt.

  • My legal ethics professor told me that if a laywer knows his client is guilty (e.g confesses to him) then if the client pleads not-guilty the lawyer must not represent him. Since allowing the client to give evidence while pleading not guilty means the lawyer is knowingly allowing his client to commit perjury. So lawyers must make an application to the judge to have themselves removed from the case. And a new lawyer will be appoointed Commented Jun 14, 2018 at 17:51
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    @ShazamoMorebucks Giving true evidence towards a false conclusion is not perjury. Commented Jun 14, 2018 at 21:47
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    @ShazamoMorebucks I would disagree. A litigation plea involves taking a position and is not a statement of fact made under oath.
    – ohwilleke
    Commented Jun 14, 2018 at 22:32
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    @Trish Ah, apologies. Commented Apr 7 at 20:26

10 Answers 10

  1. There is a big difference between knowing something and proving it. A lawyer who knows a client is guilty can take steps to prevent the state from proving guilt. (E.g., motion to exclude evidence, cross examining witnesses.)

  2. The belief that a client has committed a crime does not necessarily mean one knows what specific crime was committed. Is a killing Murder 1, Murder 2, or manslaughter?

  3. There are defenses even when an act may be a crime. E.g., self defense, insanity, justifiable.

Lawyers are not permitted to assist in perjury. E.g., allow the client to testify to something he knows is false.

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    With regard to the last paragraph, it should be noted that this does not prevent a lawyer from defending someone who pleads not guilty to a crime she or he actually committed. The plea is not made under penalty of perjury, and the accused is not forced to testify. If the accused does not testify, the accused cannot commit perjury.
    – phoog
    Commented Mar 24, 2016 at 3:50
  • What about if the defendant DOES commit perjury, and the lawyer knows it? Are they required to report it?
    – Benubird
    Commented Apr 6, 2016 at 11:43
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    The usual procedure is to ask the judge to withdraw from the case. Wink. Wink. I didn't say he committed perjury. Commented Apr 6, 2016 at 23:17
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    In England and Wales the rule for the Bar is that if a client tells you they are guilty (which is about the only time you "know") you have to advise them you are very limited in how you can represent them. In particular you can't let them give evidence - so there's no chance of them committing perjury. Commented Mar 21, 2017 at 15:33
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    In regards to the last paragraph, I submit that most defense attorneys would argue that there isn't very much that is truly knowable in terms of their client's guilt. Zealous Defense is the over-riding principle.
    – Tiger Guy
    Commented Mar 13, 2020 at 1:12

If there are any historical cases where this sort of thing happened, mentioning them would be a plus.

There are answers that address some other points, but there is something that should be made clear.

Cases where the criminal defense lawyer knows that their client is guilty of a crime are not the exception, they are the norm.

Cases where the client is definitely or probably innocent of all crimes are the rare exception, and are actually much more difficult and stressful because in those cases the only really acceptable option is a full acquittal which may be difficult or impossible to achieve.

Approximately 95% of people charged with crimes will plea guilty or be found guilty at trial.

A criminal defense lawyer's main jobs are:

(1) to hold prosecutors to their obligations to prove their case beyond a reasonable doubt with legally gathered and admissible evidence (a function that protects the public generally from law enforcement misconduct by discouraging it),

(2) to make sure that the offense of conviction is no more severe than necessary because often someone is charged with a more serious crime when the facts are better described by a less serious crime or one with different collateral consequences, and

(3) to obtain an appropriately lenient sentence for their client.

None of these jobs makes it necessary for the client to be innocent, and no one who practices criminal law with any regularity has any ethical concerns about representing someone who is absolutely certain to be factually guilty.

The criminal defense lawyer's primary ethical obligation with respect to a factually guilty defendant is not to offer testimony that the criminal defense lawyer knows to be false in an evidentiary hearing or at a trial. But, the client never has to testify at all and neither does the lawyer. A not guilty plea is not a statement made under oath and cannot be perjury. It is perfectly legal to make a not guilty plea even if you know for certain that you are factually guilty of a crime.


This applies to the USA. I cannot talk to how criminal systems of other countries operate.

Of Alan Dershowitz' "Rules of the Justice Game", from 1982 I find only the last to be completely incorrect. Public Defenders fight for justice daily, in spite of item #1. Also Number 4 is a generalization about individual officers. There are in fact officers who strive to follow the law and do things correctly. The problem is that too often the system doesn't care about the officers who don't.

  1. Almost all criminal defendants are, in fact, guilty.
  2. All criminal defense lawyers, prosecutors and judges understand and believe Rule 1.
  3. It is easier to convict guilty defendants by violating the constitution than by complying with it, and in some cases it is impossible to convict guilty defendants without violating the constitution.
  4. Almost all police lie about whether they violated the constitution in order to convict guilty defendants.
  5. All prosecutors, judges and defense attorneys are aware of Rule 4.
  6. Many prosecutors implicitly encourage police to lie about whether they violated the constitution in order to convict guilty defendants.
  7. All judges are aware of Rule 6.
  8. Most trial judges pretend to believe police officers who they know are lying.
  9. All appellate judges are aware of Rule 8, yet many pretend to believe the trial judges who pretend to believe the police officers.
  10. Most judges disbelieve defendants about whether their constitutional rights have been violated, even if they are telling the truth.
  11. Most judges and prosecutors would not knowingly convict a defendant who they believe to be innocent of the crime charged (or a closely related crime).
  12. Rule 11 does not apply to members of organized crime, drug dealers, career criminals, or potential informants.
  13. Nobody really wants justice.

Defense lawyers see the same evidence as the prosecutors do. It typically isn't hard to know if a client is actually guilty. But most defense attorneys still want the best possible outcome for their client. Many are in defense because they see the criminal justice system as terrible, so keeping anyone out of prison is virtuous.

My daughter puts it this way: "No one's life should be judged solely on their worst day." Almost everyone has value.

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    I agree that rules 1-12 are true.
    – ohwilleke
    Commented Jun 25, 2020 at 20:55

What does a lawyer do in this case? Are they required to continue to defend their client (and would that mean they may be forced to commit perjury?).

Perjury is when you lie while testifying under oath. The defendant's lawyer will not be called to testify. At no point will the defense lawyer be asked if his client committed the crime, so he is not forced to lie.

Or are they allowed to choose not to continue to represent their client in the interest of finding the truth and upholding justice?

Generally defense attorneys can ask the Judge to leave their client. Almost all defense attorneys would stick with a guilty client however. You seem to assume that justice will be upheld if the defense attorney abandons their client, but the opposite is true. Justice is when everyone is treated fairly and gets a fair trial. If the defendant doesn't have a lawyer, he may get sentenced more harshly than others who did the same crime because he does a very poor job of representing himself. That's not justice. Also if he doesn't have a lawyer who can raise objections when due process isn't followed, he could end up having his rights violated by the court. That's not justice either, and could lead to a re-trial if the mistakes are later found. Defence lawyers make sure the system convicts people the right way. Without defense lawyers, Prosecutors are just throwing complicated words at bewildered people and then throwing them in prison.


There's a couple false details in your question:

  1. Lawyers aren't force to commit perjury in the traditional sense.

    They don't lie to the court, nor are they ever under an oath of any sort. They don't testify, and even if they were (which should never happen...), any evidence that they would provide would effectively be hearsay anyway.

Or are they allowed to choose not to continue to represent their client in the interest of finding the truth and upholding justice?

Eh, that's interesting. Generally not, especially if the court assigned the lawyer to the case. This is to ensure that everyone has fair legal representation at trial. This is how to uphold justice - ensure everyone is treated fairly.

If a lawyer knows their client is guilty, it really shouldn't change anything. They will act in the interest of society as well (to a certain extent):

  • Ensure the client has adequate legal representation in court, and is subject to a fair trial
  • Try and get an appropriate and reasonable charge for the crime the client is accused of.
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    A lawyer’s evidence of a confession (admission against interest) is, as far as the hearsay rule is concerned, just as admissible as anyone else’s. Admissions are an exception to the hearsay rule. But the confession would probably be protected by legal professional privilege.
    – sjy
    Commented Jun 14, 2018 at 23:13

Sometimes everyone knows that the client is guilty, because incontrovertible evidence was found using illegal methods. Such evidence may not be used, and a jury must ignore it. Judge, prosecutor, police, jury and lawyer may all know that the client is guilty and the client can still go free.

And even if the lawyer knows that the client is guilty, the same crime might get a sentence between five and ten years, for example, and the lawyer should present the case to try to get five years prison for the client and not ten.

There was a recent case in the USA: The police got a warrant to attach a tracking device to the car of a suspected drugs dealer. The tracking device disappeared, most likely the suspect took it away. The police got a warrant to search his home claiming he likely stole the device and evidence could be found at his home. They searched his home and found plenty of evidence of drug dealing.

His lawyer, fully knowing the client was guilty of drug dealing, challenged the validity of the warrant. I don't know the exact reason, most likely taking something attached to your car into your home and turning it off is not theft, but a judge decided there were no reasonable grounds to expect evidence of theft of the device to be found in the drug dealers home. The search warrant was declared invalid, all evidence found was invalid, the guilty drug dealer went free. As he should. His lawyer did a perfectly fine job, the police messed up.

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    (if anyone is wondering how this is could possibly be a good thing: it forces the police to not issue invalid warrants in the future, which stops your home from being invaded by police for dumb reasons) Commented Oct 14, 2020 at 13:15
  • Is it correct that a new warrant cannot be issued based on information found from a bad warrant? And to what extent must information be excluded? E.g. if there was a dead body found on a bad warrant. Commented Feb 19, 2022 at 4:10
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    @Elaskanator Police comes to my home to search it have no warrant. They can search my home without a warrant, or they can go back without a search. The total outcome should be identical. Even if a dead body is found. Of course the police would be very tempted to somehow make their find look legal. Illegal, even though understandable.
    – gnasher729
    Commented Jan 29 at 17:14
  • Without "exigence" I am certain police are legally prohibited from entering your home without a warrant (or homeowner permission). Seeing a dead body through a window would create exigence. Commented Apr 9 at 18:13

This is the reason for Attorney Client Privilege. One of the first things any decent lawyer will tell a new client is to tell them their side of the story and do not lie. Defense Attorneys are legally bound not to release any information related to the client's personal buisness or activites. You can get disbarred for violating this. This holds for prospective clients, current clients, and former clients/prospective clients.

There are exceptions, namely if the client is seeking legal advice related to a planned but not executed crime.

From here, the defense lawyer will advise his client on how to proceed with the case. If the client wants to plea not guilty despite 10 eye witnesses, a security camera, a news media crew reporting on a separate incident, and the cops finding him with the still smoking gun and blood of the victim all over the hands, the Lawyer needs to discredit why the client "didn't do it".

A lot of this is based on the impeach-ability of the evidence. The more you can discredit the more you can get away with. This is actually difficult, but not impossible. Consider the Kasey Anthony (Casey) where the prosecution was trying to prove a mother had murdered her daughter and dumped the body. Here the fact that the girl was dead and Anthony's initial statements were bold face lies were suspect from the get go... but the stories from testimony and evidence and media were so bizare and out there, that it was hard to tell the exact timeline of events at all. The mother got off despite much of the nation pretty certain she did it because, no one could figure out what really happened.

The "Proof beyond reasonable doubt" standard for conviction means that all plausible explanations counter to the prosecution's narrative can be discounted because the evidence does not support the alternative happening. However, if you cannot believe one side over the other, then the jury is instructed to plead innocent, even if there is certainty in the fact that they did it in one of two ways.

Fun Fact: Scotland gets around this by offering a third finding, "Not Proven", which is why their cases can get bizarre. This means that the accused is released not because he is clearly innocent but because the prosecution sucks at their job. As one Scottish observer noted, it's the jury basically saying "You did not do it, and you better not do it again."

However, courts rarely reach this in the United States, because the US is one of the few countries that tolerates plea bargaining and these deals live as a gamble that the prosecution can get the guilty to admit to lesser crimes in exchange for not taking the prosecutor through the trial phase. 95% of US criminal cases are decided before the trial even starts and this is largely based on what evidence gets allowed to the trial. A drug dealer's case is far more likely to be decided based on a pre-trial motion to dismiss the seized drugs as evidence (you know, the basis of the charge) than it is by a trial. If the evidence is dismissed, the prosecutor could decide not to press the matter 'cause they have to prove that the accused was in possession of evidence that he cannot show the jury. Conversely, a defense lawyer might strongly recommend that his client take a deal in order to minimize jail time. And this is why the Defense Attorney still needs to help his client.

The defense attorney isn't supposed to give two damns about about anyone except his client. If the client does not have the tools to be honest with him, then he cannot do that. In the drug scenario, if your client is the small fish who sells for the big city kingpin drug dealer, it's in your client's interest to flip on his boss in order to escape the charges against him (or get a lighter sentence or lesser charges).

Again, with attorney-client privilege, the defense also is under no obligation to release any evidence of guilt to the prosecution. The reverse is not true. The prosecutor must release everything they will use against the accused and even stuff they won't. The defense is entitled to know if the prosecution has evidence that works in favor of the defense and can get into big trouble if they do not (see the Prosecutor in the Duke Lacrosse scandal for a great example of a guy who got into big trouble for not doing it).


Unfortunately, the job of defense lawyers is not to pursue truth. The job of defense lawyers is to try to help their clients avoid being found guilty. The legal profession thinks this makes sense because there are rules to be followed in proving a case and those rules have value in themselves, even if sometimes the rules prevent a guilty person from being found guilty. The Talmud (Jewish law) forbade attorneys in their courts of law, based on the logic that lawyers do not promote the pursuit of truth.

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    The prosecutor doesn't want the truth either, he or she wants a conviction, and the harshest conviction possible. The idea is that between prosecutor and defense lawyer a fair result is reached.
    – gnasher729
    Commented Jun 15, 2018 at 21:44
  • @gnasher729 Would that those who work in the legal system would pursue justice, not what benefits "their side".
    – user3270
    Commented Nov 18, 2019 at 16:16
  • @user3270 That's what s/he said. When both sides are trying to benefit their side, the equilibrium they manage to come to is probably close to the truth. Commented Oct 14, 2020 at 13:16

It's always the duty of a lawyer to support the laws (especially the constitution) and ensure that there is a fair administration of justice. It's a wonderful principle of American jurisprudence that those accused of criminal or civil culpability are innocent until proven guilty, and centuries worth of blood has been shed for that standard to prevail in the free world. All people are entitled to the benefits of law, and some of the most profound safeguards of our liberties were molded in controversies involving the favor of some of the most heinous individuals (I may have just paraphrased a supreme court decision from long ago (; ). But, in the greater scheme of things, its more conscionable to have 1,000 guilty people roaming the streets, than to have a single innocent one in prison. It's the job of a defender to pursue that asymptotic goal with fervor and zeal. That alone justifies the career.

  • Note that "innocent until proved guilty" is not unique to America. It is one of the principles American law inherited from English law (and it was not unique to there). Commented Jun 15, 2018 at 12:42

While the defense lawyer cannot knowingly make a false statement, he or she is free to make true statements to lead the jury to a false conclusion. It is simultaneously possible that the client committed the crime and that the prosecution has no credible evidence that the client did so. In his or her closing argument, the defense lawyer can accurately and in good faith rant and rave that the prosecution's entire case rests on a few pieces of circumstantial evidence that wither in the face of even the slightest scrutiny. After all, the defense lawyer's job is to use every available legal and ethical means to secure the best outcome for the client.

The burden of proof is on the prosecution. To meet this burden, the prosecution must prove every element of the crime beyond a reasonable doubt. A defense lawyer need not prove the client did not commit a crime to secure an acquittal, though the goal certainly is to convince the jury of the client's innocence; the defense need only raise reasonable doubt as to an element of the crime. For example, if the charge is first-degree murder, premeditation is an essential element. If the prosecution fails to establish premeditation or the defense at least raises reasonable doubt as to premeditation, the defendant must be found not guilty of first-degree murder regardless of any other evidence. A wise mentor of mine put it this way: The prosecution's job is to build a chair; the defense's job is to knock out one leg.

The American justice system is adversarial, meaning it runs on the principle that if each side's counsel zealously advocates on behalf of his or her client, which in the prosecution's case is the public at large, the truth will tend to emerge and justice will tend to prevail. Rules of evidence designed to prevent unfair bias, due process, Constitutional restraints on searches and seizures, and the like are safeguards designed to ensure fairness in the legal process. In some cases, these same safeguards impede the truth-seeking mission of the justice system. “Technicalities” such as the suppression of illegally obtained evidence further the public policy goal of deterring police misconduct that, if left unchecked, could lead to many false convictions. The cost of pursuing this goal is that guilty people sometimes go free. The same logic applies to the role of lawyers in our adversarial system. In the long run, zealous advocacy should lead to the justest outcome; in individual cases, it may not. Society has made the judgment that the benefits of our adversarial system and the protections embedded in it outweigh the costs.

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