As the discussions of the earlier novels show, ethical dilemmas seldom disturb Grisham's characters; their goals, rather than morality, direct their behavior. However, the characters in The Client, at least Mark and Reggie, and also Harry Roosevelt, do feel the pull of ethics. More so than in the other books, here Grisham broaches the problem of how to decide to do the right thing. Whatever readers might debate about the standards of Jake Brigance or Mitch McDeere, both Mark and Reggie definitely do have internalized moral compasses. The task Grisham sets for himself in this novel is to dramatize how challenging it really is for good people to do good things.

Reggie knows that a lie will save Mark (if the prosecutors believe him): He can say that he had been silent earlier because he was scared of the authorities and that Clifford told him nothing about Senator Boyette. But Reggie cannot counsel her client to lie in court. And although Mark brags that he wants to lie and charges that she is endangering him by not letting him lie, her advice meshes with his own instincts. He cannot make himself lie to the authorities, so he declines to say anything.

Mark's ultimate respect for the truth's sanctity is one of many indications of his strong morals. In the opening section, he lectures Ricky that the little boy can only smoke one cigarette a day and cannot, under threat of being beaten-up by Mark, take drugs or alcohol. When he sees Clifford prepare for suicide, Mark's impulse is to intervene and try to remove the hose; Mark cannot simply leave, as Ricky pleads for them to do. He later explains to Reggie, "I don't know. It was like I just had to do something once I realized what was going on. I couldn't run away. He was about to die, and I just couldn't ignore it. Something kept pulling me to his car. Ricky was crying and begging me to stop, but I just couldn't." Nor, after Clifford shoots himself, can he let the body lie in the woods, perhaps undiscovered for days, so he calls 911 to report the death. All the wretched events that follow spring from this effort to save someone's life; Mark deserves better. Although Mark may be a wiseacre and may mislead the police early on, fundamentally, he is a good person who learns the sad truth that doing good is very hard.

Dianne Sway presents another standard of behavior, security. She adamantly refuses to urge Mark to cooperate and to enter a witness protection program unless the authorities can guarantee her and her sons' safety. When challenged that her recalcitrance keeps Mark in custody, she retorts, "Sir, I'd rather have him in a detention center than in a grave." To the prosecutors, Mark is a witness who can give them what they need; to Dianne (and Reggie), Mark is a real person who needs assurance and protection. The prosecutors do not account for the human factor.