Warp core ejection system
The warp core ejection system was a system aboard warp-capable vessels designed to eject the warp core in the event of a warp core breach in order to prevent the destruction of the ship.

Activation of the ejection system typically required security clearance by the chief engineer or a senior officer. This tactic is generally considered to be a last ditch effort to save a ship during a crisis situation and is often unreliable at best. 

In the alternate reality of 2258, the  ejected and detonated several of its warp cores in order to boost the ship out of the gravitational pull of a black hole created with red matter. ()

In 2368, the Romulan Star Empire experimented with an interphase generator on board a science vessel. The experiment went wrong and destroyed their graviton generator and resonator coil causing a warp core breach. The  crew and the Romulans ejected the core, but Parem, Geordi, and Ensign Ro got phased. The situation was resolved when Data creates an Anyon field and returns Geordi and Ensign Ro to normal with Geordi ordering Engineering to stop the power transfer and to shut down the engines before the muon wave causes a warp core breach. ()
 
In early 2372, the 's ejection system failed after a power surge triggered a core breach. The excess power was eventually drained via the deflector array, averting the breach. ()

Also in 2372, the True Way sabotaged the  by removing the warp core ejection system, leaving the crew unable to stop a warp core breach which later destroyed the vessel. ()

The  ejected its warp core in 2375 to seal a subspace tear created by a isolytic burst. ()

's warp core was ejected on several occasions: 
In 2371 by B'Elanna Torres, under the influence of the consciousness of Chakotay, to prevent Voyager entering a dark matter nebula. ()
In 2374, after a stream of tachyons triggered a core overload. The core was captured by the Caatati, but later recovered. ()
The Silver Blood USS Voyager was forced to eject its warp core shortly before its destruction in 2375. The ejection allows the ship to drop out of warp, but caused further damage to the already disintegrating vessel. ()
The Doctor as the Emergency Command Hologram had the ability to order a core ejection. In 2378, he did so in order to pay for Captain Janeway's release from the Hierarchy. ()

In 2377, the  ejected its core, after problems with the ejection subroutines, to avert an antimatter explosion from destroying the Antarian Trans-stellar Rally. ()
de:Notfallausstoß des Warpkerns

Activation 

Activation of the ejection system usually involved a voice command to the computer, however the core could also be ejected through an engineering station. ()

The voice command syntax for ejecting the warp core had a standard structure and required an authorization code. ()

"Computer, prepare to eject the warp core, authorization {authorization code, e.g. "Torres omega 539"})."
The computer would respond by saying:
"Warp ejection systems enabled."
Then a final command would be necessary to eject the core.
"Computer, eject the warp core."
Warp