If testimony affirming an event or saying is given by a source who does not sympathize with the person, message, or cause that profits from the account, we have an indication of authenticity. An enemy generally is not considered to be biased in favor of a certain person, message, or cause. Suppose one of the witnesses to the accident was a friend of the one driving the red car. This witness admitted that his friend was the one who ran the red light. The new detective weighs this testimony as somewhat stronger than the testimonies of the other eyewitnesses. A witness who would be considered somewhat unfriendly to the driver of the blue car attested to his innocence. John Adams, the second president of the United States, was known for his high standards of integrity, although this did not prevent his political enemies from attacking him. Alexander Hamilton was one such enemy. In a scathing fifty-four-page pamphlet published to hurt Adams in a forthcoming election, Hamilton accused him of having “great intrinsic defects of character,” “disgusting egotism,” “eccentric tendencies,” “bitter animosity,” and an “ungovernable temper.” Yet Hamilton made no charges of corruption, and he acknowledged Adams’s patriotism and integrity.’ If Adams’s mother or wife had spoken of his integrity, we might have reason to believe them, yet with reservation. When even his enemies acknowledged his integrity, the matter is pretty well established.’

3. Embarrassing admissions support historical claims. An indicator that an event or saying is authentic occurs when the source would not be expected to create the story, because it embarrasses his cause and `weakened its position in arguments with opponents. “5 The police officer asks both drivers if they have previously disobeyed a traffic signal. The driver of the red car says “no.” The driver of the blue car admits that he caused an accident ten years ago because he ran a red light. The detective may tend to believe the entire testimony of the driver of the blue car over that of the red car driver because he willingly shared information although it would tend to embarrass or hurt him. He appears to be attempting to tell the truth. Law professor Annette Gordon-Reed wrote articles arguing that Thomas Jefferson, the third president of the United States, fathered children by his slave Sally Hemings. Before DNA results proved her correct, one of the arguments she employed in support of her position related to the Principle of Embarrassment. A declaration from a close Jefferson relative recorded the observation that it was obvious that Jefferson’s “blood ran in “the veins” of Sally Hemings’ children and that one child could be mistaken for Jefferson. She argued that this testimony must be regarded as strong evidence indeed. “Declarations against interest are regarded as having a high degree of credibility because of the presumption that people do not make up lies in order to hurt themselves; they lie to help themselves,” she wrote. In other words, this statement by Jefferson’s relative damaged the reputation of Jefferson and his family, given the social prejudices of the time when it was made. A relative would not likely have invented a statement that would hurt himself. Therefore, this statement weighs in favor of the argument that Sally Hemings bore children for Jefferson. 

Source: The Case for the Resurrection of Jesus, by Dr. Gary Habermas