I'm not sure whether you mean "expectations" or "exceptions" in this question, but I think the answer is the same. During Kira's trial, Vandara accuses her and invokes the rules of the society to show why Kira should die. Vandara says that Kira should have been taken to the Field "when she was born and still nameless" because "it is the way." Jamison agrees it is the way, but says that "exceptions can be made." The rules also say that a fatherless and imperfect child should have died, but again, Jamison says, "exceptions may be made."
Previously, Kira had invoked the law when Vandara and the other women were about to stone her. If someone was killed in a dispute without bringing the dispute to the guardians, the "causer-of-death must die." That rule and its expectation were followed, leading to Kira's trial.
However, the rule evidently did not apply to the guardians themselves. As the story unfolds, Kira learns that Thomas's, Jo's, and her own parents all died under questionable circumstances. Kira finally learns that her father was not killed by beasts, but was injured, blinded, and left to die by Jamison, who later became guardian. All the guardians knew of that event; at least some had witnessed it. Kira suspects her mother may have been poisoned to death rather than having succumbed to an illness. The guardians are circumventing the rules of society, creating exceptions for themselves, contrary to what the citizens believe and expect.