Result of Bad Company
Instrumental in the vastraharan of Draupadi. When Draupadi questioned the court how she could be used as a 'bet' when Yudhishtra himself had already lost. Karna in his explanation said that since Yudhishtra himself had lost, it was immaterial what happened later, every of his belongings, now was lost to Dhuryodhana. He further added insult with these commands, "O Duhsasana, seize the garments of the Pandavas and the robes of Draupadi and hand them over to Sakuni".
Karna abets in the killing of Abhimanyu, the son of Arjuna. Six warriors including Karna disarm Abhimanyu and proceed to injure him severely with arrows. Abhimanyu’s death is ghastly and even in this instance, Karna acts on the command of Duryodhan. He could have advised Duryodhan against killing Abhimanyu in such a cruel manner against Dharma. This act tarnishes Karna’s image further because six fighting against one is against the laws of Dharma.
Even upon learning that his brothers were the ones that were being discriminated, he did not try to reason with his friend, Dhuryodhana.