(a) A case shall be held to involve or to grow out of a labor dispute when the case involves persons who are engaged in the same industry, trade, craft or occupation; or who are employees of one employer; or who are members of the same or an affiliated organization of employers or employees; whether such dispute is between one or more employers or associations of employers and one or more employees or associations of employees; between one or more employers or associations of employers and one or more employers or associations of employers; or between one or more employees or associations of employees and one or more employees or associations of employees; or when the case involves any conflicting or competing interests in a "labor dispute" (as hereinafter defined) of "persons participating or interested" therein (as hereinafter defined).

(b) The term "labor dispute" includes any controversy concerning terms or conditions of employment, or concerning the association or representation of persons in negotiating, fixing, maintaining, changing or seeking to arrange terms or conditions of employment, or concerning employment relations, or any other controversy arising out of the respective interests of employer and employee, regardless of whether or not the disputants stand in the relation of employer and employee.

(c) A person or association shall be held to be a person participating or interested in a labor dispute if relief is sought against him or it and if he or it is engaged in the industry, trade, craft or occupation in which such dispute occurs, or is a member, officer or agent of any association of employers or employees engaged in such industry, trade, craft or occupation.