In the 1999 case United States v. Roy Lee Johnson, the U.S. Supreme Court addressed whether a defendant's prior conviction could be used to enhance his sentence for a subsequent offense under the Armed Career Criminal Act (ACCA). The ACCA imposes a mandatory minimum sentence of 15 years for defendants who have three previous convictions for violent felonies or serious drug offenses. Johnson had been convicted in state court of burglary and was later federally indicted on gun charges. The government sought to use his prior burglary conviction as one of the three necessary to trigger an enhanced sentence under ACCA. However, Johnson argued that because he had not been represented by counsel during his burglary trial, using this conviction violated his Sixth Amendment right to counsel. The Supreme Court ruled against Johnson, holding that even if there were Sixth Amendment concerns with using uncounseled convictions as predicate offenses under ACCA, those concerns did not apply when such convictions are constitutionally valid due their being obtained via waiver of rights or through plea agreements.

In the dissenting opinion for United States v. Roy Lee Johnson, it was argued that the majority's decision to uphold Johnson's conviction under 18 U.S.C §922(g)(1) - a federal law prohibiting felons from possessing firearms - was incorrect. The dissent contended that this statute should not apply in cases where the defendant had no knowledge of his felon status, as ignorance of one’s legal status is fundamentally different from ignorance of the law itself. They believed that convicting someone who did not know they were committing a crime contradicts basic principles of criminal justice and due process rights guaranteed by the Constitution. Furthermore, they pointed out inconsistencies in how courts have interpreted "knowingly" within various statutes and called for clearer guidelines on its application to avoid potential miscarriages of justice.