Starfleet General Order 1, otherwise known as the Prime Directive, stipulates that no Federation personnel may interfere in the natural development of an alien world. All captains, crews, and miscellaneous members of Starfleet hold this rule as sacrosanct and are often willing to sacrifice anything, even their own lives, to ensure it remains unviolated.
Of course like any rule, it routinely gets broken by Starfleet captains who find themselves having to rescue or defend their crews, or power-hungry admirals looking to further their own interests. In these cases, however, some violations of the Prime Directive are worse than others.
Defying The Edo
Exploring the galaxy and seeking out new civilizations with the Prime Directive to guide you may sound like an interesting and noble pursuit until you encounter a culture whose rules run so contrary to your own that following the Prime Directive seems ridiculous.
This was the case in The Next Generation episode, "Justice," where Wesley Crusher was sentenced to death by the Edo for accidentally destroying some freshly planted flowers. Although a majority of Star Trek fans would have probably opted to have the young Mr. Crusher gone, Captain Picard saved his life in defiance of Edo's ridiculous laws.
Insurrection
It’s amazing how many of Starfleet’s top brass end up going rogue. In Star Trek: Insurrection, the corrupt Admiral Dougherty plans to displace the peaceful society of the Ba’ku in order to steal the precious regenerative properties of their planet. Planning to transport them in a portable holodeck to skirt the Prime Directive, Dougherty didn’t count on a renegade Data exposing the Starfleet personnel sent to observe them.
Though Data’s actions would normally be considered unconscionable, the worse offense to the Prime Directive was Admiral Dougherty’s. However, he paid for his crime at the hands of the renegade Son’a, Ru'afo.
Simulated War
By all accounts, war is a bloody affair that the Federation seeks to avoid at all costs. In the original series episode, “A Taste of Armageddon,” Captain Kirk learns that the inhabitants of Eminiar VII conduct their war via computer simulation, and people who “die” in these simulations must step into killing machines to fulfill the agreement between the opposing sides.
When the Enterprise is “destroyed” in a simulation, Kirk violates the Prime Directive by destroying the computers running the war rather than sacrificing his crew to the killing machines. However, he has also condemned the planet to continue its war with all the horrific destruction and bloodshed that accompanies it.
The Picard
First Contact missions can be dicey, as Starfleet personnel has to be able to infiltrate the society being observed without being identified as aliens. In “Who Watches the Watchers?” an accident leaves a native of the proto-Vulcan society on Mintaka III critically wounded, so Dr. Crusher beams him aboard the Enterprise to treat him.
There, he encounters Captain Picard and believes him to be a god. Despite an attempted memory wipe, the individual begins to spread his newfound religion amongst his people. Horrified at this gross violation of the Prime Directive, Picard beams down to explain the entire situation to the Mintakans, leaving them with the truth about space travel rather than the belief in his divinity as a lesser violation of the Prime Directive.
Janeway’s Delta Quadrant Deals
Being 70,000 light-years away from home put Captain Janeway and the crew of the USS Voyager in a precarious position, as they needed to secure provisions and resources for the journey home. To do that required some bending on the rules from time to time, and the Prime Directive was no exception.
Captain Janeway would sometimes trade technology for those provisions, in violation of the Prime Directive. Perhaps the worst instance of this is when she gave holodeck technology to the Hirogen, a race of ruthless hunters. They promptly used that technology to think up new and inventive ways to hunt their prey, including the less technologically sophisticated denizens of the Delta Quadrant and the Voyager crew itself.
The Feeders Of Vaal
Supercomputers who run primitive societies are seemingly everywhere in the Star Trek universe. In the original series episode, “The Apple,” Captain Kirk and his landing party encounter “The Feeders of Vaal,” a simple people who live in an idyllic tropical paradise on Gamma Trianguli VI.
Immune to disease and childless, it is revealed that these people exist to feed the supercomputer known as Vaal, who in turn keeps them young and in good health. To save his crew from Vaal’s wrath and give The Feeders of Vaal autonomy, Captain Kirk destroys the supercomputer, violating the Prime Directive. Although free, The Feeders of Vaal would now have to fend for themselves, without the supercomputer’s protection.
The Nazi Planet
You’d think that a Starfleet cultural observer sent to aid a lawless culture in developing an orderly society would know better than to use Nazi Germany as a template, but that’s what historian John Gill did in the original series episode, “Patterns of Force.”
Hoping to mimic Nazi Germany’s efficiency, Gill instead led the planet Ekos to adopt all forms of that loathsome iteration of fascism, including the “Final Solution:” obliterating the planet Zeon, Ekos’ enemy. This violation of the Prime Directive was inadvertent, as Gill was manipulated by a ruthlessly ambitious Ekosian, but the results were nonetheless horrific.
The Omega Glory
Captain Ronald Tracey of the USS Exeter couldn’t wait for the promotion to admiral before going berserk and sacrificed his crew for viral immunity and a chance at immortality on planet Omega IV. Driven mad by a deadly virus that was cured by the planet’s atmosphere, he perpetuated a gross violation of the Prime Directive by giving the Kohms, a primitive faction native to the planet, several hand phasers which they used to slaughter the Yangs, their enemies.
Thankfully, Captain Kirk and his crew managed to overturn Captain Tracey’s mad plans, but the damage to the planet's society had been done.
A Private Little War
Although the Federation abides by the Prime Directive and the principle of non-interference, other galactic powers in the Star Trek universe have no such regulations, and routinely interfere wherever and whenever they see fit. The Klingons did this in the original series episode “A Private Little War,” when they armed the primitive villagers of the planet Neural with firearms.
They immediately took aggression against the hill people, whom they had trading relations with, and began slaughtering them in a grab for power. Captain Kirk’s solution for this was to arm the hill people with firearms, breaking the Prime Directive. Although this act may have brokered a temporary peace through a balance of power, it also condemned the planet to horrific bloodshed and endless war should any ceasefire escalate to an all-out war.
Sisko’ Secret
Perhaps the worst violation of the Prime Directive was a desperate ploy by Captain Benjamin Sisko to save the Alpha Quadrant and the Federation from being conquered by the Dominion. Facing imminent defeat, Sisko realized that the Federation/Klingon alliance needed the intervention of another galactic power to tip the scales against Dominion/Cardassian aggressions.
The neutral Romulans seemed like a viable option, and Sisko tried hard to win them over through diplomacy. Unfortunately, deceit and murder turned out to be the only way to get them on-side. Granted, the Romulans were not a pre-warp society, but Sisko’s tricking them into a protracted and bloody war that ran against their natural development remains the worst violation of the Prime Directive to date.