These questions may also arise after the election if the losing party asks for the annulment of the election by inserting itself against behaviours that could have influenced the election. The type of behaviour that can justify reversing the election result depends on the facts of each and the adherence of the NLRB itself at the time of the decision on the case; While the board has established some principles that have been in place for decades, it has radically changed policy in other areas, often as a result of changes in the ideological composition of the board after changes in the party occupying the White House, in order of the participations discussed below. The employer generally has to address these issues before the scheduled election; it cannot subsequently refuse to negotiate the theory that the device is not suitable because it was not made in time. On the other hand, this rule does not prevent the employer from later challenging the vote of a single worker on the grounds that he is not a worker within the meaning of the law, as is the case, for example, in the case of a supervisor. It is legitimate for an employer to recognize a union without going through a choice made by the NLRB, as long as the union of more than half of the employees of the collective agreement unit has received assistance. However, this evidence cannot be valid if the employer has provided illegitimate assistance to the union in collecting these cards or if another union has filed a petition to represent these workers before the employer grants recognition. The Board of Directors is also excluded by law from holding an election within a unit if it has held a valid election in that unit in the last twelve months. However, this rule does not prevent the Board of Directors from requiring a repeat election if it finds that the election was not valid, either because of the conduct of the parties or for other reasons. The Board of Directors may also conduct an election in a unit larger than the former unit and allow staff members who voted in the previous election to vote in the second ballot. When the board changed under the next White House government, the Council returned to its fair election assurance policy under General Knit.  (a) Election approval agreements with the final regional directors of post-election disputes.