Common law as source of law
5 ILCS 50/1
Act 50. Common Law Act
50/1. Rule of decision
§ 1. The common law of England, so far as the same is applicable and of a general nature, and all statutes or acts of the British parliament made in aid of, and to supply the defects of the common law, prior to the fourth year of James the First, excepting the second section of the sixth chapter of 43d Elizabeth, the eighth chapter of 13th Elizabeth, and ninth chapter of 37th Henry Eighth, and which are of a general nature and not local to that kingdom, shall be the rule of decision, and shall be considered as of full force until repealed by legislative authority.
MD Constitution, Declaration of Rights, Art. 5
Article 5. Application of common law and statutes of England; trial by jury
(a)(1) That the Inhabitants of Maryland are entitled to the Common Law of England, and the trial by Jury, according to the course of that Law, and to the benefit of such of the English statutes as existed on the Fourth day of July, seventeen hundred and seventy-six; and which, by experience, have been found applicable to their local and other circumstances, and have been introduced, used and practiced by the Courts of Law or Equity; and also of all Acts of Assembly in force on the first day of June, eighteen hundred and sixty-seven; except such as may have since expired, or may be inconsistent with the provisions of this Constitution; subject, nevertheless, to the revision of, and amendment or repeal by, the Legislature of this State. And the Inhabitants of Maryland are also entitled to all property derived to them from, or under the Charter granted by His Majesty Charles the First to Caecilius Calvert, Baron of Baltimore.
West's Ann.Cal.Civ.Code § 22.2
§ 22.2. Common law of England; rule of decision
The common law of England, so far as it is not repugnant to or inconsistent with the Constitution of the United States, or the Constitution or laws of this State, is the rule of decision in all the courts of this State.