Labor Unions in the Private Sector

WHO MAY UNIONIZE IN THE PRIVATE SECTOR? For purposes of collective bargaining, the following persons may join, form or assist a labor organization:

[1] All persons employed in commercial, industrial and agricultural enterprises;
[2] Employees of government-owned or controlled corporations without original charters established under the Corporation Code;
[3] Employees of religious, charitable, medical or educational institutions, whether operating for profit or not;
[4] Front-line managers, commonly known as supervisory employees;
[5] Alien employees;
[6] Working children;
[7] Homeworkers;
[8] Employees of cooperatives; and
[9] Employees of legitimate contractors not with principal but with the contractor.
References: 

PD 442's Article 243. Coverage and employees’ right to self-organization. All persons employed in commercial, industrial and agricultural enterprises and in religious, charitable, medical, or educational institutions, whether operating for profit or not, shall have the right to self-organization and to form, join, or assist labor organizations of their own choosing for purposes of collective bargaining. Ambulant, intermittent and itinerant workers, self-employed people, rural workers and those without any definite employers may form labor organizations for their mutual aid and protection. (As amended by Batas Pambansa Bilang 70, May 1, 1980)

PD 442's Article 244. Right of employees in the public service. Employees of government corporations established under the Corporation Code shall have the right to organize and to bargain collectively with their respective employers. All other employees in the civil service shall have the right to form associations for purposes not contrary to law. (As amended by Executive Order No. 111, December 24, 1986)

PD 442's Article 245. Ineligibility of managerial employees to join any labor organization; right of supervisory employees. Managerial employees are not eligible to join, assist or form any labor organization. Supervisory employees shall not be eligible for membership in a labor organization of the rank-and-file employees but may join, assist or form separate labor organizations of their own. (As amended by Section 18, Republic Act No. 6715, March 21, 1989)