One of the principles of statutory interpretation in common law countries is that statutes are not deemed to displace common law rules unless this intent is clearly indicated by the statute. This is often phrased in the form: "a statute in derogation of the common law is to be strictly construed."
This preserves an inferior and older law of general application, in favor of a newer, superior in authority, and more specific law.
For example, a law regarding federal government employee life insurance policy beneficiaries does not expressly provide that the designation of someone as a beneficiary is invalidated in the event that the beneficiary murders the person insured by the life insurance policy.
Notwithstanding the language in the statute that says that a designated beneficiary of the life insurance policy is entitled to the benefits upon the insured's death, the courts have held that the common law rule that a beneficiary of a life insurance policy who kills the insured is not entitled to the benefits of the policy overrides the express statutory statement that the designated beneficiary of a federal government employee life insurance policy is entitled to the benefits when the insured dies.
This result was reached based upon the rule that the common law is not displaced by a statute unless an intent to do so is clearly indicated by the statute.
There may be other exceptions to the rules of lex specialis, lex superior, and lex posterior, but this one is the first that came to mind.
Some states, such as Utah, however, have overruled this interpretative provision. Utah Code § 68-3-2(1) states that:
The rule of the common law that a statute in derogation of the common
law is to be strictly construed does not apply to the Utah Code.