Final answer:
The Supreme Court established the after-acquired evidence rule in McKennon v. Nashville Banner Publishing Co. This rule allows illegally obtained evidence to be admissible in court if the government can show it would have been obtained legally through independent means.
Step-by-step explanation:
In McKennon v. Nashville Banner Publishing Co., the Supreme Court established the after-acquired evidence rule. This rule states that even if evidence is obtained illegally or in violation of constitutional rights, it can still be admissible in court if the government can show that they would have obtained the evidence lawfully anyway through independent means. In other words, if the government would have inevitably discovered the evidence through legal means, then it can be used despite its initial illegal acquisition.