To determine the true meaning of the law, the courts often take into consideration the legislative history. This refers to the materials that the lawmakers were studying, and the things that they said during the process of passing the law. Legislative history consists of things like the official analysis by legislative advisers, summaries and explanations sent to the lawmakers with the text of the bill, committee reports on the bill, letter sent to the governor by the legislature explaining why the law needed to be enacted, newspaper editorials authored by the lawmakers who sponsored the bill, and the text of debates and speeches made on the floor of the legislature prior to votes on the bill.
When you are reading a law, there frequently are no test the prior versions of it. For example, here is the dog bite statute of Connecticut and its annotations:
§ 22-357. Damage to person or property
If any dog does any damage to either the body or property of any person, the owner or keeper, or, if the owner or keeper is a minor, the parent or guardian of such minor, shall be liable for the amount of such damage, except when such damage has been occasioned to the body or property of a person who, at the time such damage was sustained, was committing a trespass or other tort, or was teasing, tormenting or abusing such dog. If a minor, on whose behalf an action under this section is brought, was under seven years of age at the time such damage was done, it shall be presumed that such minor was not committing a trespass or other tort, or teasing, tormenting or abusing such dog, and the burden of proof thereof shall be upon the defendant in such action. For the purposes of this section, “property” includes, but is not limited to, a companion animal, as defined in section 22-351a, and “the amount of such damage”, with respect to a companion animal, includes expenses of veterinary care, the fair monetary value of the companion animal and burial expenses for the companion animal.
(1949 Rev., § 3404; 1953, Supp. §§ 1400c, 1842d; 1969, P.A. 439, § 1, eff. June 16, 1969; 2013, P.A. 13-223, § 1.)
The annotations are highly abbreviated, and mean the following:
“In the book of revised statutes for the year 1949, this statute appears as section 3404. In the 1953 supplement to the book of revised statutes, revisions appear in sections 1400C and 1842D.”
I actually don’t know the meaning of the abbreviation “P.A.” but I suspect that it refers to an enacted law which was signed by the governor in 1969 and became effective on June 16, 1969. The same would be true of the one in 2013.
It is an arduous process to see the prior versions of laws and the legislative materials that went with them. Where an understanding of the history is critical, one has to go to the old books and find whatever has been published there. These types of books are found only in the most inclusive law libraries, and legislative history (which is so important to understanding what the lawmakers had in mind) frequently can be found only in the capital of the state in question.
Another problem with tracking down versions and legislative history is that only so much of it was published in any one state. For example, in the state of California, legislative history pertaining to statutes was published in book form as of somewhere around 1950. Prior to that, one has to travel to Sacramento and physically go to the library of the legislature as well as the library of the governor in order to dig through whatever materials they retained.
There is one possible shortcut for you. The legal publishing company called West has volumes of annotated codes for each state, and the annotations contain prior versions of the statutes themselves, and sometimes important sections of the legislative history. My suggestion is that if you are doing a survey of the laws of various states you go to a major law library where they have the West annotated codes for all the states in question, and look up the statutes.