Before you use a case that you've found in your secondary source research, it is good practice to check that the case is still applicable to your issue.
Case citators use symbols and and annotations to indicate the treatment of a case in subsequent decisions and the current status of the case.
Casebase (Lexis Advance) and Firstpoint (Westlaw) use their own set of symbols to indicate the subsequent treatment of the case.
Casebase symbols indicate whether the case decision has received positive, negative, cautionary or neutral treatment in subsequent judgments.
Firstpoint has symbols for the litigation history of your case as well as for cases citing your case. These indicate how your case was treated in subsequent judgements.