STATUTORY LAW
You can find freely available statutory law online for federal, state and municipal jurisdictions. These electronic sources are often the legislating bodies themselves, and they'll have obvious URLs, such as Congress.gov. There are other sources, however, such as
that have statutory law, as well as regulatory law and case law. These can be taken to be legitimate sources, but check to see how often they are updated.
REGULATORY LAW
Federal regulatory law can sometimes be found on agency websites, such as osha.gov or can be found here:
STATE LAW & LEGISLATION
The state of Illinois conveniently puts its legislation, codified statutes, and regulatory law all in one place:
Law and legislation from other states is available freely online as well, it just requires some searching. Websites should be .gov or .us unless the state pays a third party to administer its digital legislative information. Going through a state's official website is the surest way to know that it's legit.
Once you've found the correct website, explore what information is actually there (e.g.: bills from previous legislatures). Look for Bill Tracking and Bill Text information. Bills are often introduced in several legislatures before becoming law.
MUNICIPAL LAW
Municipal law can often be found through individual municipal websites. The Municipal Code of Macomb can be found through the Macomb City website, but the link points to:
CASE LAW
FEDERAL
Case law is often published online by the court where the case was heard, you can find federal cases through govinfo.gov at this link:
STATE
Illinois Court Opinions can be found here: (GOOGLE OTHER STATE COURT SYSTEMS)
Laws passed by both chambers of the United States Congress and signed by the President of the United States are given sequential numbers that start afresh at the beginning of each Congress - we just began the 118th Congress in January 2023. When the 118th Congress passes its first law, it will be:
P.L. 118-1
Laws passed by both chambers of the Illinois General Assembly and signed by the Governor of the State of Illinois are given sequential numbers that start afresh at the beginning of each General Assembly - Illinois just began the 103rd General Assembly in January 2023. When the 103rd G.A. passes its first law, it will be:
P.A. 103-1
Municipal Codes can only be found online in codified form.