Lat. ejusdem generis argument. Lat. idem, “identical”; genus, “genus”.

1. Argument from genus

The argument from the genus is based on essential definition. It transfers to the species, and ultimately to the individuals, the properties, duties, representations, any and all characteristic attached to the genus they belong to, S. Classification; Categorization; Definition.

2. Extending to the genus: the generic clause “… and the like”

Generic clauses are phrases such as “… and the things of the same kind”, “… and the like”. The text has the form:

This provision concerns a, b, c, and things of the same kind.

Universal Declaration of Human Rights, Article 2[1].
Everyone is entitled to all the rights and freedoms set forth in this Declaration, without distinction of any kind, such as race, color, sex, language, religion, political or other opinion, national or social origin, property, birth or other status. (My italics)

If an object x is not included in the enumeration “a, b, c…” but if it is possible to consider that it belongs to the category defined by the enumeration, then the generalizing clause “and all beings of the same kind” applies the provision concerning a, b and c to x.

This shows that the individuals enumerated are mentioned not only for their own sake, but also as prototypes from which a new category must be derived, S. Analogy (II).

This provision concerns cars, motorcycles, and all private means of transportation.

Cars and motorcycles are considered to be prototypical members of the category “private means of transportation” to which the provision applies. Note that the particle etc. would also open the list to new categories of individuals, but would not give any indication about the relevant common feature constituting them into a specific genus, as the provision “all private means of transportation” does quite clearly. The generic provision may either create a new category out of the enumeration of specific individuals, or explicitly mention an existing genus:

One must pay the tax on chickens, geese, and other poultry.
Conclusion: therefore on ducks and turkeys.

Chickens and geese are mentioned only as prototypical examples of the category “poultry”. One can discuss borderline cases, for example whether a peacock is really a backyard animal or a pet. In any case, there is no levy on rabbits, which don’t qualify as poultry.

On the other hand, the absence of a generic provision limits the application of the measure to the categories that are explicitly mentioned:

You have to pay the tax on chickens and geese.
Conclusion: So not on ducks.

Unless the legislator’s intention is invoked.

The use of the extensive clause is not limited to the legal field:

Fixed concrete barbecue
Warning! Do not use alcohol, gasoline or similar liquids to light or reactivate the fire.

[1] Quoted after www.un.org/en/universal-declaration-human-rights/ (01-07-2017)