Free tool · Legal Research and Writing
How to Synthesize a Rule From Several Cases: A Rule Synthesizer
Rule synthesis combines what several cases establish into one coherent statement of the law, instead of summarising each case in turn. List each case’s outcome and the factors on which the court relied. Look for the factors that are present in every case in which the claim succeeded and absent from the cases in which it failed: these suggest what makes the difference. Note factors that appear on both sides of the line, because they were not decisive. Then state the rule in general terms that explain all the results, and cite the cases that support it. A synthesis is an argument about what the cases mean, so check the opinions to confirm that the factors you list were the courts’ reasons.
Tool · Rule Synthesizer
The tenant recovers for the landlord’s failure to repair where written notice and landlord knew of defect, and does not where oral notice only and landlord did not know of defect.
Present in every winning case, and missing from a losing one: written notice; landlord knew of defect
Only in losing cases: oral notice only; landlord did not know of defect
On both sides of the line (do not decide the outcome): tenant paid rent; repair delayed
- Factors that appear on both sides of the line (tenant paid rent; repair delayed) do not decide the outcome on these cases. State them, if they matter, as factors that were not determinative.
- A synthesis is an argument about what the cases mean. Read the opinions to check that the factors you list were the court’s reasons, and not just facts that happened to be present.
Enter several invented cases on one question, each with its outcome and the factors the court relied on (separated by commas). The tool finds the factors that appear in every winning case and not in the losing ones, the factors that only appear in losing cases, and the factors that do not decide the outcome, and drafts a rule that combines them. It counts factors: whether those were really the court’s reasons is for you to check in the opinions. Runs in your browser; nothing is stored or sent.
How to use it
- State the outcome that the cases decide.
- Enter each case, whether the claim succeeded, and its factors.
- Read which factors separate winners from losers.
- Check the opinions and refine the rule.
Common questions
How many cases do I need?
At least three, with outcomes in both directions. Two cases can show a pattern by coincidence, and cases that all go one way cannot show what made the difference.
What if no factor separates the cases?
The rule may be a balancing test, or the cases may differ on factors you have not listed. Add the facts the courts stressed.
Is a synthesised rule binding?
No. It is your statement of what the authorities show. Only the holdings of binding cases bind.
Learn the law behind the tool
This tool is part of our Legal Research and Writing course, with lectures, concept maps, flashcards, interactive exercises and a capstone case. Legal Research and Writing: Predictive Writing.
More free law tools
General information, simplified, mainly on American law, not legal advice. States and countries differ, and real cases turn on facts that a tool cannot capture.