Collective Bargaining Protection Act of 1991

Collective Bargaining Protection Act of 1991 - Amends the National Labor Relations Act to make it an unfair labor practice for an employer to offer or grant: (1) permanent replacement employee status during an economic strike between the labor organization that is acting as the collective bargaining representative involved in the strike, for a 12-week period beginning on the date of the hiring of the first such replacement; or (2) any employment preference to an individual who worked or indicated a willingness to work during an economic strike over an employee who exercised specified rights during such strike and who is working for, or has unconditionally offered to return to work for, the employer.

Amends the Railway Labor Act to prohibit any carrier or their officer or agent from offering or granting: (1) permanent replacement employee status in a craft or class during a labor dispute, for a 12-week period beginning on the date of the hiring of the first such replacement; or (2) any employment preference to an individual who worked or indicated a willingness to work in a craft or class during a labor dispute over an employee who exercised specified rights during such dispute and who is working for, or has unconditionally offered to return to work for, the carrier.

Revises National Labor Relations Act provisions for National Labor Relations Board (NLRB) prevention of unfair labor practices to require that priority be given to preliminary investigations of charges of unfair labor practices by an employer or labor organization filed before an employer hires a replacement employee. Requires the NLRB officer or regional director to try to issue a complaint before the expiration of the 12-week period (for the ban on hiring permanent replacement employees during an economic strike) if such official has reasonable cause to believe such charge is true, after such preliminary investigation.