最優先指令（Prime Directive）とは宇宙艦隊一般命令・規則の一般命令1条の指令条項であり、宇宙艦隊は他文明の内政干渉及び自然な発展の妨害や干渉を行ってはならないという最も優先されるべき束縛原理の一つである。最優先指令では宇宙艦隊士官はいかなる惑星においてもその社会秩序の妨害を行うことは禁じられている。（TNG:決別の儀式） 最優先指令に対する違反行為は、その行動への十分な正当性がない限り軍法会議にかけられ、厳罰に処される。例え宇宙艦隊の人員がこの指令を無視する程の強い倫理的な問題があると判断して違反行為を行ったとしても、指令での規定が優先される。（TNG:神からの警告、VOY:転送・4万光年）
The Directive states that members of Starfleet are not to interfere in the internal affairs of another species, especially the natural development of pre-warp civilizations, either by direct intervention, or technological revelation. When studying a planet's civilization, particularly during a planetary survey, the Prime Directive makes it clear that there is to be "No identification of self or mission. No interference with the social development of said planet. No references to space, other worlds, or advanced civilizations." (TOS: Bread and Circuses) Starfleet personnel are required to understand that allowing cultures to develop on their own is an important right and therefore must make any sacrifice to protect cultures from contamination, even at the cost of their own lives.
In the 23rd century, the Directive applied equally to both Starfleet and civilian personnel (TOS: Bread and Circuses), In the 24th century, the status of the Prime Directive concerning Federation citizens is in flux. Under the rules as defined in the Directive, a Starfleet crew is forbidden from removing citizens who have interfered with the culture of a world. Violating the directive can result in a court-martial for the offending Starfleet officer or crew. At the same time, Nikolai Rozhenko was found to be in violation of the Directive for attempting to help the citizens of a dying planet he was observing.(TNG: Angel One、Homeward)
Originally the Directive was a shield for primitive worlds. If such a world was in danger, Starfleet had been known to order ships to save that world, provided it could be done without violating the Directive. (TOS: The Paradise Syndrome)
The Directive was later amended, prohibiting Starfleet officers from intervening even if non-intervention would result in the extinction of an entire species or the end of all life on a planet or star system. By the 24th century the Federation had begun applying the Prime Directive to warp-capable species, refusing to interfere in internal matters such as the Klingon Civil War. (TNG: Pen Pals、Homeward、Redemption、Redemption II)
There are two general exceptions to the Prime Directive:
The first is in cases where an extreme threat to the Federation exists. General Order 24 authorizes a Captain to order the destruction of an entire civilization under certain circumstances. (TOS: A Taste of Armageddon、Whom Gods Destroy) The "Omega Directive" is triggered when a Starfleet vessel encounters an Omega molecule. When the Omega Directive is in force, the Prime Directive is rescinded. (Due to issues of security, only Starfleet officers ranked Captain and above are privy to knowledge of this directive.) (VOY: The Omega Directive)
The second is in the event that a protected civilization has already been exposed to the knowledge of superior technologies and off-world civilizations. (TOS: A Piece of the Action、A Private Little War) In these cases, Starfleet officers often attempted to repair the damage caused by either inadvertent or deliberate exposure. (TNG: Who Watches The Watchers)
Some Starfleet Captains, including James T. Kirk, have noted that the Prime Directive only applies to living growing civilizations and have overlooked the directive where it has been more convenient to do so, particularly in cases where societies have been enslaved or in a state of total stagnation (also known as an arrested culture). (TOS: Errand of Mercy、The Return of the Archons、The Apple)
That position fell out of favor by the 24th century. Captain Kathryn Janeway once noted that 23rd century Starfleet officers were "a little too slow to invoke the Prime Directive".(VOY: Flashback)
The Starfleet also had no qualms about dealing openly with civilizations that, while possessing the requisite knowledge of advanced technology, choose not to make use of it. An example of such a culture would be the Ba'ku. Though the Ba'ku were initially treated as "protected" by the Prime Directive (Admiral Dougherty's and the Son'a's machinations aside) due to the appearance that they were a pre-warp culture, it later became known that they in fact were not.
- On stardate 3156.2, Captain Kirk caused the Landru computer to self-destruct by convincing it that it was harming the society that it was designed to protect. Kirk justified himself by claiming that Landru was preventing the society from showing any form of creativity or passion. (TOS: The Return of the Archons)
- In the same year, Eminiar VII's warring computer was destroyed to prevent Captain Kirk from having to execute General Order 24. (TOS: A Taste of Armageddon)
- Also that year, on stardate 3715.3, Kirk ordered the Enterprise to destroy the Vaal computer that was caring for the inhabitants of Gamma Trianguli VI, justifying his action on the grounds that the computer was denying them any chance to grow and evolve and fulfill their potential, either individually or culturally. (TOS: The Apple)
- Later that year, Kirk persuaded Spock's mirror double to work for change in the Terran Empire. (TOS: Mirror, Mirror)
- On stardate 3156.2, Captain Kirk prevents Maab from killing Eleen, thereby allowing her unborn son to become Teer of the tribes. (TOS: Friday's Child)
- The crew of the Enterprise investigate the loss of contact of historian and cultural observer, John Gill, who was assigned to the planet Ekos. They discover that Gill deliberately committed a flagrant violation of the Prime Directive when he attempted to reorder the planet's society into a benign version of Nazi Germany, with himself as Fuhrer. Furthermore, the intervention proved a total disaster with a subordinate, Melakon, quietly seizing power and adopting the same murderous racial supremacist ideologies as the original. With the cooperation of the local resistance, Capt. Kirk and Mr. Spock, arrange for the government to be overthrown. (TOS: Patterns of Force)
- The following year on stardate 4211.4, Kirk and the crew of the Enterprise provide weapons for the Hill People of the planet Neural after the Klingons had already provided a rival group with weapons. Kirk felt that it was justified to even the odds in this instance. It should be noted that the weaponry given to the Hill People was equivalent but not superior to that owned by the rival group, however the Hill People were pacifists prior to the Federation's arrival. (TOS: A Private Little War)
- On stardate 4842.6, Captain Kirk became entangled with the native population of the planet Amerind after his memories were damaged by an alien device. He was proclaimed a god by the indigenous population of Native Americans, and called "Kirok". He married Miramanee, the daughter of the chief, and fathered a child with her. He was rescued months after his "loss" by Commander Spock and Dr. McCoy, who were seen in full uniform by the indigenous people. (TOS: The Paradise Syndrome)
- Later in 2268, Captain Ronald Tracey violated the Prime Directive by using his phaser to help the Kohms in their dispute with rival faction, the Yangs. He was later arrested by Captain Kirk for his violation. (TOS: The Omega Glory)
- In 2319, then Captain Mark Jameson of the USS Gettysburg would supply weapons to terrorist leader Karnas on Mordan IV in exchange for the release of Federation hostages. However he also supplied Karnas' rivals with equivalent weaponry plunging the planet into decades of civil war. Forty five years later he refers to this action as his 'interpretation' of the Prime Directive to Jean-Luc Picard. Admiral Jameson also mentions that he falsified records of this event to Starfleet indicating such interpretation is not consistent with the spirit of the Prime Directive. (TNG: Too Short a Season)
- Captain Picard violated the Prime Directive circa stardate 41255 when he prevented the Edo of Rubicun III from executing Wesley Crusher for having unwittingly broken one of their laws. Picard felt that absolutely enforced law can never result in true justice. (TNG: Justice)
- In the same year, when Picard discovered that the Brekkians were exploiting the Ornarans by keeping them addicted to a drug that had once been used for medicinal purposes, although he didn't take direct action to reveal the drug's true purpose, he left the freighter that they had been using to make the trades damaged to give the Omarrans a chance to 'wean' themselves off the drug (TNG: Symbiosis).
- In 2365, Lieutenant Commander Data made a violation by answering a call for help from Sarjenka of Drema IV and maintaining communication with her for eight weeks. A highly emotive discussion took place between the senior staff on whether or not to interfere by resolving the problems on the planet. There were mixed views where Doctor Katherine Pulaski and Lieutenant Geordi La Forge believed that it was the right thing to do while Lieutenant Worf felt that there was no degree to the Prime Directive and that it should be followed absolutely, almost blindly. Picard initially ordered Data to cease communication with Sarjenka but he took a change of heart considering the "Human" condition and went ahead with Data's "In for a penny, in for a pound" proposal for neutralizing the seismic activity of the planet. (TNG: Pen Pals)
- Under the Klingon Right of Vengeance, Lieutenant Worf confronted Duras for murdering K'Ehleyr in early 2367 and killed him in the ensuing fight. Under normal circumstances, Worf (as a Starfleet officer) would have faced serious disciplinary action alone but Duras was contending against Gowron to be Chancellor of the Klingon Empire, following the death of K'mpec. Worf's killing of Duras directly affected the outcome of the race for leadership of the Empire, resulting in Gowron becoming Chancellor – a violation of General Order #1. Understanding that Duras was both the murderer of his former mate and the son of the man who was directly responsible for his father's death, and the fact that Worf was acting under Klingon custom at that moment, Captain Picard later told Worf that his Klingon duties had become incompatible with his Starfleet ones and asked if Worf wanted to resign his commission. Worf decided to remain in Starfleet, and although Picard forgave Worf, he also placed a reprimand on his permanent record. (TNG: Reunion)
- A malfunction in a observation team's duck blind caused an explosion which was viewed by the People of Mintaka III. This caused the Mintakans to revert into belief of an Overseer. Captain Picard violated the Directive to make the people understand the science team's purpose. (TNG: Who Watches The Watchers)
- Benjamin Sisko and his crew on Deep Space 9's orders were "to do everything short of violating the Prime Directive" to make Bajor and the Bajoran people ready for Federation membership. (DS9: Emissary)
- In 2369, Chief Miles O'Brien was reprimanded for having assisted a Tosk in escaping from a group of Hunters. Having done so both violated the Prime Directive and went against Commander Sisko's orders. (DS9: Captive Pursuit)
- Several weeks later, Doctor Julian Bashir wondered if assisting the Ennis and the Nol-Ennis escaping their moon prison might be breaking the Prime Directive. Sisko told him he was aware of that fact. (DS9: Battle Lines)
- Despite the fact the Cardassians were behind it, Admiral Chekote ruled that the Prime Directive meant that the Federation could not get involved in thwarting Jaro Essa and the Alliance for Global Unity's coup d'état against the Bajoran Provisional Government. (DS9: The Circle)
- In 2370 (Stardate 47423.9), Nikolai Rozhenko violated the Prime Directive when he acted to save natives of Boraal II from the destruction of their planet, although all steps possible were taken to prevent the Boraalians from learning what had happened to them. (TNG: Homeward)
- In 2371 (Stardate 48315.6), Captain Kathryn Janeway destroyed the Caretaker's Array to prevent the Kazon from using it aginst the Ocampa, even after Tuvok said "[destroying the array] will alter the balance of power... the Prime Directive would seem to apply". Janeway justified her action by stating, "We didn't ask to be involved...but we are." (VOY: Caretaker)
- In an alternate timeline in 2371, Captain Janeway and Lieutenant Paris inadvertently violated the Prime Directive when they traveled back in time on a class M-Planet in the Delta Quadrant – their presence alone affected events that occurred in that timeline. (VOY: Time and Again)
- In 2372, Lieutenant Torres made a proposition to Captain Janeway to assist the Pralor Automated Personnel Units in developing a way to propagate themselves but Janeway refused as it would be a violation of the Prime Directive and that the repercussions are almost impossible to imagine. However in order to save the lives of her shipmates from the Units after she was abducted, B'Elanna was forced to assist the Pralor in developing further units. However after successfully building a prototype, she learned that this would provide the Pralor with a substantial tactical advantage, almost certainly changing the war between the Pralor and Cravic Units in their favor. (VOY: Prototype)
- In the early to mid 2370s, Captain Rudolph Ransom and the crew of the USS Equinox murdered several nucleogenic lifeforms and used their bodies for fuel to greatly enhance their warp drive. Ransom felt that he was justified under Starfleet Regulation 3 but Captain Janeway rejected his justification, doubting that the regulation covered murder. (VOY: Equinox、Equinox, Part II)
- In 2374, Captain Benjamin Sisko committed a major Prime Directive violation when he worked with Elim Garak to force the Romulan Empire to enter into Dominion War under false pretenses. The Romulans up to this point had remained neutral in the conflict. Sisko felt that Federation and Klingon Empire would lose the war with the Dominion if they did not gain another ally in the war. Both Sisko and Garak, with the knowledge and approval of Starfleet Command, created false evidence that ultimately convinced the Romulans that the Dominion were planning to renege on the Peace Treaty between the two governments and mount a full scale invasion. Participation in the war resulted in massive military and civilian casualties, and likely resulted in major economic, political, military and social shifts for the Romulan Society. But for Sisko's intervention, the Romulans may not have suffered such consequences.
- In 2375, Worf again entangled himself in internal Klingon politics when he challenged Gowron for leadership of the Empire due to the latter's deliberate mishandling of Klingon forces in an attempt to destroy the reputation of General Martok. Worf defeated Gowron in single combat, and for a few moments became Chancellor of the Klingon Empire. However, he immediately abdicated in favor of Martok, who assumed the mantle. Worf had previously been authorized by Captain Sisko to use whatever means necessary to resolve the issue, as Gowron was risking the entire war effort to satisfy his political agenda. (DS9: Tacking Into the Wind)
- Also in 2375, Tom Paris is demoted to the rank of Ensign and incarcerated in Voyager's brig for a period of thirty days for violations including insubordination, unauthorized use of a spacecraft, reckless endangerment and conduct unbecoming an officer. All of these offenses are the result of Paris' attempt to save the Monean World Ocean. When Paris confronts Janeway, prior to the actions resulting in his demotion and imprisonment, she explains to him that helping the Moneans would be a violation of the Prime Directive. Paris is never directly charged with violating the directive, however. Janeway's punishment seems unusually harsh, compared to how other similar violations are handled in other incidents: Paris is denied visitors, decent food, and access to the Captain Proton holonovels. In fact, the only thing preventing Janeway's punishment from being tantamount to psychological torture is that he is allowed access to a PADD. (VOY: Thirty Days)
- The Prime Directive was instigated long after Earth launched the Friendship 1 probe in 2067. (VOY: Friendship One) Indeed, the Directive was not yet in force as late as the 2160s, when the crew of the starship Horizon left behind books on technology and culture that radically altered the course of civilization on the planet Sigma Iotia II. (TOS: A Piece of the Action)
- While the Prime Directive was not officially formulated until after the 2160s, the fundamental principles were an important part of Earth Starfleet procedures as early as 2152. (ENT: The Communicator)
- A similar order, known as the Temporal Prime Directive, was also eventually created to prohibit giving individuals in/from the past information about their future. Captain Kirk has a record of seventeen temporal violations. Admiral Janeway tells her younger self that it was best to 'just ignore' the Temporal Prime Directive. (VOY: Endgame) The Temporal Prime Directive was first mentioned by Braxton in VOY: Future's End, Part II, implying that it was created sometime between the 24th and 29th centuries. However, subsequent episodes (including VOY: Relativity) suggested that it had already been created during the 24th century, at the latest.
- Even though the inhabitants of Kolarus III were of a pre-warp civilization, an away team including Captain Picard, Lt Cmdr Data and Lt Cmdr Worf visited the planet in 2379 without making any attempt to integrate themselves into the planet's society (i.e. surgical alterations) and taking advanced technology such as the Argo. Such actions would have been a clear violation of the Prime Directive but no apparent action was taken against Picard by Starfleet Command. (スタートレック：ネメシス)
- Warp capability does not provide a "blank cheque", so to speak—even with a warp-capable species, Starfleet is reluctant to interfere. Captain Janeway is initially reluctant to help an android race to procreate despite their obvious advanced technology. (VOY: Prototype) She also refuses to provide the warp capable Kazon with replicator technology or allow them access to the Caretaker's array on the grounds that it would "disrupt the balance of power in this [Delta] Quadrant." (VOY: Caretaker)
- Precedents exist for not allowing other species to interfere with the development of pre-warp cultures. Although the Ferengi have not adopted the Prime Directive, USSVoyager prevents two of them from posing as gods to a pre-warp civilization. Lt. Commander Tuvok justifies this by pointing out that Starfleet bears some responsibility for their presence on the other side of the erratic Barzan Wormhole. (VOY: False Profits; TNG: The Price)
- According to Rear Admiral Norah Satie on stardate 44769.2, Jean-Luc Picard had violated the Prime Directive a total of nine times since taking command of the USSEnterprise-D three and a half years prior. (TNG: The Drumhead)
"The Prime Directive is not just a set of rules; it is a philosophy... and a very correct one. History has proven again and again that whenever mankind interferes with a less developed civilization, no matter how well intentioned that interference may be, the results are invariably disastrous."
- - Captain Picard (TNG: Symbiosis)
"There are no options. The Prime Directive is not a matter of degrees. It is an absolute. "
"I have a problem with that kind of rigidity. It seems callous and even a little cowardly."
- - Worf and Pulaski, debating the Prime Directive (TNG: Pen Pals)
"...all of this is just philosophy. Sarjenka is not a subject for philosophical debate, she is a person."
"He's got a point. The Prime Directive was designed to protect, not destroy."
"So Doctor, you draw the line at the death of millions."
"Same situation if it's an epidemic rather than a geological catastrophe?"
"How about a war? A generations-long conflict that is killing millions. Do we interfere? Now we're less secure in our moral certitude. And what if it's not death? What if it's an oppressive government which is enslaving millions? You see, the Prime Directive has many different functions, not the least of which is to protect us. It keeps us from allowing our emotions to overrule our judgment."
- - Data, Pulaski, and Picard, debating the Prime Directive (TNG: Pen Pals)
"I have reconsidered. I spent the whole night reconsidering. And what I've decided goes against all my principles. Some day my people are going to come up with some sort of a doctrine, something that tells us what we can and can't do out here; should and shouldn't do. But until somebody tells me that they've drafted that...directive...I'm going to have to remind myself everyday that we didn't come out here to play God."
- - Archer, sensing the need for the Prime Directive (ENT: Dear Doctor)
In the TOS novel Strangers from the Sky, Vulcans had developed their own set of non-interference canon of laws in the 1870s. However, they did not hold Humans - with whom they made first contact - bound to these restrictions.
In the ENT novel By the Book, Captain Archer had to decide whether to supply one of the two cultures he met with technology to bring them on the level of the more advanced society.
In the TNG novel Double Helix: Double or Nothing the Resolution of Non-Interference was drafted and signed by all Federation members in 2175. By the 2190s the Prime Directive was in full force.
In the TOS novel Prime Directive, a Scale of Culture was developed in the early 2200s in order to measure cultural development of a civilization and monitor its development.
According to the CD-ROM game Star Trek: 25th Anniversary, one of the most serious violations of the Prime Directive was an event known as "The Galahad Incident" caused by an unauthorized entry of the USS Galahad into the civil war on Shiva Omicron IV in 2208. The Galahad used its phasers to stun an army of the Jerion faction during an attempted massacre, causing the unconscious Jerions to be themselves massacred. This eventually led to the destruction of the Jerion culture. This event became a test case for measuring the competency of a starship captain. Captain Joshua Mulrone Grant was court-martialed and imprisoned for his part in the genocide. At his court martial, he stated, "the Human Directive is the real Prime Directive."
The Temporal Prime Directive is referenced in the novel Federation, by Judith Reeves-Stevens. In this novel, the Temporal Prime Directive existed in both the time of TOS and in the time of TNG. There, both Kirk and Picard knew how to follow the Temporal Prime Directive, even though neither was capable of time travel (or at least not willful time travel).
In the alternate future seen in the Deep Space Nine Millennium book trilogy, the Federation, in the middle of fighting a fierce war with the Bajoran Ascendancy, suspended the Prime Directive. The timeline was later reset thanks to the efforts of the crew of Deep Space 9.
According to the FASA role-playing guide The Federation, the first captain being court-martialed for violating the Prime Directive was Captain James Gunther Smithson. On stardate 1/2803 he disabled the nuclear weapons of two governments on Vega Proxima preventing nuclear war. Smithson was relieved of command and dishonorably discharged from service.