In the 1995 case of Charles Carlisle v. United States, the Supreme Court ruled on a matter concerning sentencing guidelines for drug-related offenses. The defendant, Charles Carlisle, was convicted of conspiracy to distribute cocaine and marijuana as well as possession with intent to distribute these substances. He argued that his sentence was improperly enhanced under the U.S Sentencing Guidelines based on an incorrect determination of drug quantity involved in his crimes. The court held that when determining sentences for drug offenses, all relevant conduct should be considered - not just conduct related directly to counts of conviction but also any additional quantities attributable through joint criminal activity reasonably foreseeable by the defendant. In this context "relevant conduct" includes acts and omissions committed or aided by the defendant or for which he would be otherwise accountable. Carlisle's argument hinged upon whether certain amounts were part of a single course of conduct or common scheme; however, it was found that even if they weren't included in his offense level calculation, there would still have been enough remaining quantity to justify his base offense level under sentencing guidelines. Therefore,the Supreme Court upheld Carlisle’s original sentence concluding that district courts are allowed considerable discretion when making factual findings about defendants' relevant behavior during sentencing proceedings.

In the dissenting opinion for Charles Carlisle v. United States, the justice argued that there was a significant difference between failing to object at trial and actively waiving one's rights. The defendant in this case had not been informed of his right to testify on his own behalf, which is a fundamental constitutional right. Therefore, he could not have knowingly waived it. Furthermore, the justice pointed out that even if Carlisle had known about this right and failed to assert it during trial proceedings, such failure should be considered as forfeiture rather than waiver because waiver requires an intentional relinquishment or abandonment of a known right or privilege which did not happen in this case according to him/her (the dissenter). He/She also disagreed with majority’s reliance on Federal Rule of Criminal Procedure 29(c) stating that its interpretation by them was incorrect and overly rigid; instead arguing for more flexibility based upon individual circumstances surrounding each case.