While a collective agreement is in force, it can only be amended by a voluntary and reciprocal agreement. An amendment to the duration of the agreement must be approved by the Labour Council. In Sweden, about 90% of employees are subject to collective agreements and 83% in the private sector (2017).   Collective agreements generally contain minimum wage provisions. Sweden does not have legislation on minimum wages or legislation extending collective agreements to disorganised employers. Unseated employers can sign replacement agreements directly with unions, but many do not. The Swedish model of self-regulation applies only to jobs and workers covered by collective agreements.  Workers are not required to join a union in a specific workplace. Nevertheless, most industries, with an average union training of 70%, are subject to a collective agreement. An agreement does not prohibit higher wages and better benefits, but sets a legal minimum, much like a minimum wage. In addition, an agreement on national income policy is often, but not always, reached, bringing together all trade unions, employers` organisations and the Finnish government.  The collective agreement binds signed union members and employers who are members of an employer union that signed the agreement. These agreements are considered normally binding.
Collective agreements also include decisions on working time and overtime pay. Trade Union Pro`s collective agreements include, for example, agreements on shift work differences, travel allowances, sick pay, maternity leave benefits, leave pay and child care benefits. Collective bargaining allows workers and employers to voluntarily agree on a wide range of issues. Nevertheless, it is limited to some extent by federal and regional laws. A collective agreement cannot be entered into by contract, which is prohibited by law. For example, a union and an employer may use unconventional negotiations to deprive workers of the rights they would otherwise enjoy under laws such as civil rights laws (Alexander v. Gardner-Denver Co., 415 U.S. 36, 94 P. Ct. 1011, 39 L Ed. 2d 147 ).
Nor can collective bargaining be used to waive the rights or obligations that the laws impose on each party. For example, an employer cannot negotiate with collective agreements to lower safety standards that it must meet under the Occupational Safety and Health Act (29 U.S.C.A. Moreover, the collective agreement is not purely voluntary. The inability of one party to reach an agreement allows the other party to resort to certain legal tactics, such as strikes and lockouts, to exert economic pressure and to reach an agreement. Moreover, unlike trade agreements governed by national law, the collective agreement is almost exclusively governed by federal labour law, which determines issues that require collective bargaining, the date and nature of negotiations, and the consequences of non-negotiation or compliance with a collective agreement. Congress passed the National Labor Relations Act (NLRA) in 1935 (29 U.S.C.A. No. 151 and following) to establish the right of workers to collective bargaining and other group activities. The NLRA also created the National Labor Relations Board (NLRB), a federal authority empowered to enforce the right to collective bargaining (No.