have the last say

1. To express the final point or opinion in an argument or discussion, especially in a way that decisively or conclusively ends it. The whole meeting just descended into chaos as everyone tried to have the last say. David is so smug and always has to have the last say in every debate. Shouldn't the professor have the last say on this issue? She's the expert, after all.

2. To have the authority to decide how something ultimately happens or is done. As the editor-in-chief, I have the last say on the layout design for every issue. The department heads all contribute to creating the strategy, but it's ultimately the CEO who has the last say. If we disagree about what course of action to take, then who has the last say?