Article 364 Federal Labor Law

The labor unions must be constituted with a minimum of twenty employees or with three employers, at least. In the case of the labor unions of employees, when a controversy arises before the courts regarding their constitution, for the determination of the minimum number, those whose employment relationship had been terminated for cause or given as terminated within the sixty calendar days prior to the date of said constitution shall be taken into consideration.

The federations and confederations must be constituted by at least two labor union organizations.