Final answer:
The speaker is emphasizing human nature as a common thread of imperfection in moral behaviors among all people.
Step-by-step explanation:
The speaker is emphasizing human nature by stating that no one is free from telling lies or engaging in immoral actions, implying that these behaviors are inherent in all humans. This reflects a universal aspect of human nature where moral imperfections are common to everyone, regardless of their backgrounds or identities. The idea being conveyed is not specifically about truth and lies, courtroom proceedings, or immorality alone, but rather how these issues are woven into the fabric of human behavior.