Finding US cases: HeinOnline
Access via A-Z Databases page:
The Introduction to the U.S. Supreme Court Library provides a brief overview of the Supreme Court as well as a description of the database.
The Official Reports contain:
Click here for a definition of 'slip opinion'.
Slip opinions can be searched by date or case name:
Cases are in PDF format.
Warning: Using 
will not produce an AGLC4 citation! See Citing US cases using AGLC4 box below.
Finding US cases: Lexis Advance (US Research System)
Access from the A-Z Databases page:
Unless you know the specific Federal Court or Circuit of your case, select All Federal. Similarly, if you are unsure of the State where the case you require was decided, select All States.
If you are looking for a case on a specific subject, select a topic from those listed under Practice Area.
Example of a case:
Warning: Using 
will not produce an AGLC4 citation! See Citing US cases using AGLC4 box below.
Subsequent consideration:
Find the case and click on 
Finding US cases: Thomson Reuters Westlaw
Access from the A-Z Databases page:
Unless you know the specific Federal Court or Circuit of your case, select All Federal Cases. Similarly, if you are unsure of the State where the case you require was decided, select All State Cases.
If you are looking for a case on a specific subject, select a topic from those listed under Cases by Topic.
Example of case:
Use PDF of original image.
Subsequent consideration:
Located next to 
is a list of cases relied upon as authority by the document you are viewing. Note flags indicating later judicial consideration.
Free case law sites
Legal Information Institute (LII)
US Government Publishing Office: United States Courts Opinions
Other Library guides for finding US cases
The University of Melbourne's United States Legal Research Guide: Case Law provides excellent information on locating US cases.
Monash University's Foreign law - United States is also recommended.
This guide aims to provide links to US cases, and is not intended as an explanation of the US system.