Case law, like legislation, can change over time. Just because a decision was good law once does not mean it remains so today. A lawyer needs to be able not only to find and read case law, but also to be able to check whether it has been subject to subsequent judicial consideration and whether it remains good law.

Tools for checking a case's status

Online services offer functions to help you check the status of a case. Westlaw contains “Case Analysis” documents and Lexis+ contains “Case Overview” documents. These documents include information about where a case is reported, whether it has been judicially considered or referred to in later cases, and citations to other cases referred to in the case.

The principal traditional printed aids to locating and checking case law are the Current Law Case Citator, Year Book and Monthly Digest.

The Case Analysis helps you check whether a case can still be relied on as good law:

1. Find the case through the Cases search.
2. Select the link to the ‘Case Analysis’ in the relevant record.
3. Look at the ‘Appellate History’ and (under 'Primary References') ‘Key Cases Citing’ sections. These indicate whether the case has been overruled, reversed, affirmed or otherwise considered.
4. Also look at the 'Treatment' section (under 'Case Analytics') to view the treatment of the case by later cases and identify those later cases which have overruled, reversed, affirmed or otherwise considered the case. (You can filter by type of treatment.)

Tip: A red warning icon  is also displayed at the top of records for cases which are no longer good authority.

The 'Case Overview' document helps you check whether a case can still be relied on as good law.

1. Search for a case
2. In the search results, from the case record, select the ‘Case Overview’ link.
3. Look at the ‘Case history’ and ‘Cases referring to this case’ sections. These indicate whether the case has been overruled, reversed, affirmed or otherwise considered.

Tip: A red warning icon is also displayed in records for cases which are no longer authority.

A court in handing down a judgment may consider a previous decision in several ways. A previous decision may be:

• Approved - A higher court may state that another case heard by a lower court was correctly decided.
• A decision may be Applied - A court may apply the reasoning of a previous case in a current case, where the facts are different from those of the previous case.
• A decision may be Followed - A court may be bound by a previous decision where the material facts were substantially the same as in the instant case.
• Or a decision may be Distinguished - A court may not follow a previous and otherwise binding decision because there is a difference in, for example, the material facts. The previous case remains good law.
• In some instances a decision may be Disapproved - A higher court may state that another case heard by a lower court was wrongly decided. The court indicates that the previous case may not be good law - but does not expressly overrule it.
• Alternatively a previous decision may be Doubted - A court while not expressly overruling a previous case may give reasons to show that it may have been wrongly decided.
• Or a decision may be Not followed - A court may choose not to follow the decision of a court of coordinate jurisdiction where the material facts were substantially the same as the instant case.

Finally, a decision in a different case may be Overruled - A court may expressly overrule the ratio decidendi of an inferior court’s decision in another case.

In addition, if a case is appealed to a higher court, the decision of the lower court may be:

• Affirmed – The same case is held to have been correctly decided by the lower court. It is good law.
• Or a decision may be Reversed – The same case is held to have been wrongly decided by the lower court. It is not good law.

Furthermore, under the doctrine of parliamentary supremacy, a decision in a case may be superseded by legislation.

Importantly, if a case has been reversed, overruled (or superseded by legislative provisions) it is no longer good law and should not be relied on as authority.

Checking the status of case law in the Library

Use the Current Law Case Citator.

1. Look up the case in the Citator:

• begin with the volume covering the period during which the case was reported;
• check each subsequent volume in turn;
• for consideration within the last year, use parts of the Current Law Monthly Digest.

2. Each time you find an entry for the case:

• note whether the case has been overruled, reversed, affirmed or otherwise considered and the reference to the later case;
• this reference is to the Current Law Year Book digest and is given in the form of year and paragraph number e.g. 93/459.

3. Look up the entry in the Current Law Year Book, you will find details of the case which considered your original case:

N.B. For cases reported before 1948 you may need to use other digests in the law reference section (e.g. the Faculty Digest):