The Five Types of Legal Reasoning and Argument

Five Methods of Legal Reasoning (and Argument)

1. Rule-Based Reasoning:

Rule-based reasoning is the most important type of legal reasoning. In rule-based reasoning, you take a rule (a statute or a case holding) and apply it to a set of facts. (This is a type of deductive reasoning.) Richard Neumann has stated that rules have at least three parts: "(1) a set of elements, collectively called a test; (2) a result that occurs when all the elements are present (and the test is thus satisfied); and (3) . . . a causal term that determines whether the result is mandatory, prohibitory, discretionary, or declaratory." (Richard K. Neumann, Jr., Legal Reasoning and Legal Writing: Structure, Strategy, and Style 16 (2005). In addition, some rules have "one or more exceptions that, if present would defeat the result, even if all the elements are present." (Id.) An example of a rule would be that intentional infliction of emotional harm occurs if 1) the defendant’s conduct is outrageous, 2) the defendant’s conduct is intentional, 3) the defendant’s conduct causes, 4) severe emotional distress. The rule would be satisfied if the facts of the present case satisfies all the elements of the rule. For example, if an ex-boyfriend calls an ex-girlfriend several times in the middle of the night to harass her (outrageous conduct; intentional conduct) and this causes (causation) her severe emotional distress (element 4), intentional infliction of emotional distress has taken place.

2. Reasoning by Analogy

Reasoning by analogy concerns finding similarities. Reasoning by analogy in the law occurs when one argues that the facts of the precedent case are like the facts of the present case so that the rule of the precedent case should apply to the present case. (A is like B, so the rule from A applies to B.) An example of reasoning by analogy is that the rule that one who keeps a wild animal, like a tiger, on her property is strictly liable for any damage caused by that animal also applies to pit bulls because a pit bull, although not a wild animal, is inherently dangerous just like a wild animal. The two cases are never exact; reasoning by analogy is a question of degree. The writer must convince the reader that the facts of the two cases are similar enough that the rule from the precedent case should apply to the present case.

3. Distinguishing Cases

Distinguishing cases is the opposite of reasoning by analogy. In distinguishing cases, one argues that the facts of the precedent case are not like the facts of the present case so that the rule from the precedent case does not apply to the present case. For example, a toy poodle is not like a wild animal because toy poodles are not inherently dangerous so that the rule from the wild animal cases that an owner of a wild animal should be strictly liable for any damage caused by that wild animal should not apply to toy poodles.

4. Reasoning by Policy

With policy based-reasoning, the writer argues that applying a particular rule to a case would create a precedent that is good for society. For instance, in early products liability cases, lawyers argued for strict liability when a product injured a consumer because manufacturers could better spread the cost of injuries than consumers. Policy-based reasoning can also be combined with reasoning by analogy. For instance, one can argue that the policy behind the rule in the precedent case also applies to the present case so the rule in the precedent case should also apply to the present case.

5. Inductive Reasoning

Inductive reasoning is reasoning from the specific to the general. Lawyers use inductive reasoning to synthesize rules. In other words, lawyers take the holdings from several cases and by synthesizing those specific cases, they come up with a general rule. To synthesize a rule look at the similarities among the facts of the precedent cases and the differences among the facts of the precedent cases. Also, look at the reasoning behind the holdings.

Case 1 holding: A person who owns a tiger that escapes and causes personal injury is strictly liable for that personal injury.

Case 2 holding: A person who owns a tiger that escapes and causes property damage is strictly liable for that property damage.

Case 3 holding: A person who owns a pit bull that escapes and causes personal injury is strictly liable for that personal injury.

Case 4 holding: A person who owns a toy poodle that escapes and causes personal injury is not strictly liable for that personal injury.

Synthesized rule: A person who owns an inherently dangerous animal that escapes and causes personal injury or property damage is strictly liable for that personal injury or property damage.

Reasoning: Tigers, which are wild animal, and pit bulls, which are breed to be aggressive, are inherently dangerous, while toy poodles are not. When two innocent parties are involved, the law usually holds the party liable that keeps dangerous things, like wild animals. The rule applies to both personal injury and property damage.

Update:  For more on legal reasoning and other keys to law school success, see my book, Think Like a Lawyer: Legal Reasoning for Law Students and Business Professionals (2020).

 

(Scott Fruehwald)