Determine the makeup of the law reference. Determine whether it is from the government legal code (a statute) or from the Constitution. There are citation protocols for both, so determine the type of reference before beginning.
Find out what the parts of the law reference are called. You can find this information on the front page of the statute or the constitution. Law reference numbers are divided into sections, articles, subsections and parts. For example, as stated above, IC 9-30-5 is formally labeled Title 9, Article 30, Chapter 5.
Use the Blue Book Uniform System of Citation that is widely used among legal professionals for statutes. You can find this book in a library or bookstore. Spell out the titles of the statute ("Title 9, Article 30, Chapter 5 of the Indiana Code states..."). Use the same rule for constitutions.
Follow the statute designations with a comma and the source of the law reference. In the example, the source would be Indiana Code. The in-text citation becomes, Title 9, Article 30, Section 5, Indiana Code.
End the citation with the year that the statute was enacted, placed in parenthesis. The final citation should resemble, Title 9, Article 30, Section 5, Indiana Code (2007).