Shimon ben Azzai interpreted the phrase "and the owner of the ox is absolved" (Exodus 21:28) as absolution from paying half-kofer — half of the ransom payment owed when an ox kills a person.
His reasoning is elegant. An ox that kills another ox must pay damages. An ox that kills a person must also pay. In the case of ox-versus-ox, a mued (habitual gorer) pays full damages while a tam (first-time gorer) pays half-damages. By analogy, when an ox kills a person, the mued's owner should pay full kofer while the tam's owner should pay half-kofer.
But the Torah says "the owner of the ox is absolved." Ben Azzai reads this as specifically absolving the tam's owner of the half-kofer that the analogy would otherwise require. Without this verse, the parallel to ox-versus-ox damages would have created an obligation to pay half-ransom even for a first-time goring that killed a person.
This interpretation reveals the Mekhilta's method of reading "absolution" clauses. When the Torah says someone is "absolved," it does not simply mean they face no consequences. It means they are absolved of a specific obligation that we would otherwise have imposed through legal reasoning. The Torah had to explicitly remove the half-kofer obligation because the logic of the legal system would have generated it automatically. Absolution is not the absence of law — it is an active override of what the law would otherwise require.