On the sidesticks of Airbus aircraft, there is a Priority Takeover button. Wikipedia has this to say:
In typical Airbus side-stick implementations, the sticks are independent. The plane's computer either aggregates multiple inputs or a pilot can press a "priority button" to lock out inputs from the other side-stick.
On US flight 1549, the CVR transcript shows that Sully hit the Priority T/O button, after the co-pilot (Skiles) handed over control of the aircraft:
15:27:23.2 - Sully: My aircraft.
15:27:24.0 - Skiles: Your aircraft.
15:27:26.5 - FWC: Priority left.
I'm curious as to why there's a need for this button at all?
Here's a short video on YouTube, demonstrating this: