Answer to Question 1
An impasse in bargaining is a temporary deadlock or hiatus in negotiations that in almost all cases is eventually broken either through a change of mind with or without the aid of a mediator or through the application of economic force, be it a strike or a lockout.
Answer to Question 2
An impasse in bargaining in a multiemployer unit is not an unusual circumstance justifying unilateral withdrawal. It is a recurring feature in the bargaining process, which in almost all cases is eventually broken. Parties at impasse commonly recognize that sooner or later they will agree on the terms for a new collective bargaining agreement.