The Emergency Medical Holographic program (EMH) was a sophisticated hologram developed in the early 2370s by Starfleet and used on most Federation starships in the late 24th century. It was designed to provide short-term advanced assistance during emergencies in sickbay to the extent of literally replacing a starship's medical officer. (DS9: "Doctor Bashir, I Presume"). The formal name of the program was EMH Program AK-1 Diagnostic and Surgical Subroutine Omega-323. As of 2377, there have been four versions of the EMH, called Mark I, II, III, and IV. (VOY: "Projections", "Life Line")
In 2268, while testing the ill-fated M-5 multitronic unit aboard the USS Enterprise, Spock lamented to Dr. Leonard McCoy on the misfortune that computer programming had not yet advanced far enough to replace a starship's surgeon. McCoy retorted that he'd rather resign than be replaced. (TOS: "The Ultimate Computer")
Starfleet commissioned the brilliant holo-programmer Doctor Lewis Zimmerman at the Jupiter Station Holoprogramming Center as the embodiment of modern medicine. The EMH Mark I was first activated in 2371, and was programmed with over 5 million possible treatments from the collective information of 2000 medical references and the experience of 47 individual medical officers. The EMH was also supplemented with contingency programs and adaptive programs to learn while serving as a supplement of a normal medical staff in cases of emergency. It contains 50 million gigaquads of computer memory, which is "considerably more than most highly developed humanoid brains." (VOY: "Life Line")
Dr. Zimmerman, proud at his achievement, decided to program the EMH with both his physical, and most notably, psychological likeness. Unfortunately, Dr. Zimmerman did not take into account that his own personality made a poor bedside manner for a medical doctor. The resulting hologram was arrogant and irritable, and as a result was poorly received by many Starfleet doctors. This resulted in nicknames like "Emergency Medical Hotheads" and "Extremely Marginal Housecalls." (VOY: "Life Line") Some biological Starfleet doctors even went so far as to object to the use of the EMH. Doctor Beverly Crusher swore that she would never use one, although she was forced to do so in order to create a distraction while the Borg tried to assimilate the USS Enterprise-E, allowing her, her medical staff, and her patients, notably Lily Sloane, to escape from sickbay. (Star Trek: First Contact)
Starfleet would later request Dr. Zimmerman to design a holoprogram to operate as a full-time doctor in any posting where life support or living space was at a premium and the primary mission did not require the doctor to leave sickbay. As a result, the research and design for the Long-term Medical Holographic program was begun in mid-2373. (DS9: "Doctor Bashir, I Presume")
Deep Space 9 did not have an EMH installed initially, as it was incompatible with the station's Cardassian technology. An EMH was installed in 2373 as a way to transfer its data into the Long-term Medical Holographic program (LMH). (DS9: "Doctor Bashir, I Presume")
Eventually it was concluded that the EMH Mark I was defective, and they were bounced out of the medical corps. While an ashamed Dr. Zimmerman tried to have them decommissioned, Starfleet reassigned them to scrub plasma conduits on waste transfer barges. Later the Mark I's were also deployed in other menial tasks, like dilithium mining.
Of at least 678 Mark I's created, 675 were reassigned, but at least some escaped by virtue of their ship being lost in the Delta Quadrant; one aboard the USS Voyager, one aboard the USS Equinox, and the backup copy of Voyager's EMH which was in the possession of the Kyrians – assuming these were not counted among those reconfigured. (VOY: "Life Line", "Author, Author", "Living Witness")
Most notably The Doctor, a Mark I serving on the USS Voyager, ran almost continuously for years and was forced to expand his programming extensively to keep up. This EMH originally objected to being the replacement for the entire medical staff, as the EMH program was only meant to function for a maximum of 1,500 hours (62.5 days); after this time, memory degradation would occur. Fortunately, with the help of his colleagues, his program was altered to overcome this shortcoming. (VOY: "The Swarm")
While the Mark I's outward appearance was a copy of its inventor, a disillusioned Dr. Zimmerman changed the outward appearance of the Mark II. Furthermore, the patterns of behavior of the following versions were designed to be more pleasant and courteous. To achieve this, Zimmerman initially tried to improve on the programming of the Mark I, but eventually decided to create the Mark II from scratch. In addition to that, new ship designs like the USS Prometheus enabled full mobility for the EMH, as the whole ship was outfitted with holographic projectors.
By 2378, the Mark I programs were reconfigured to work at a Federation mining colony in replacement of other forms of labor. These programs, having been reassigned to their new function, were able to obtain bootlegged copies of the holonovel Photons Be Free and view them. One of the EMH miners found the holonovel "provocative". (VOY: "Author, Author")
Voyager's EMH Mark IEdit
After the EMH Mark II supplanted the "inferior" Mark I, the only remaining versions to fulfill their original programming were aboard the USS Voyager and the USS Equinox, which were both stranded in the Delta Quadrant and had to implement the emergency holograms for extended periods of time. However, a notable caveat was that the crew of the Equinox deleted their EMH's ethical subroutines in order to allow him to act contrary to the Hippocratic Oath. In 2376, the Equinox EMH was deleted while in Voyager's database, leaving Voyager's program, "The Doctor", as the only Mark I still operating as an EMH. (VOY: "Equinox", "Equinox, Part II")
Voyager's EMH (The Doctor) developed a distinct personality over the ship's seven-year-long journey to the Alpha Quadrant. Despite this, The Doctor was not granted the rights of a living person by a Federation Arbiter, although he did determine that The Doctor fulfilled the requirements of an artist under the law. The Arbiter did, however, encourage The Doctor to pursue recognition as a sentient being at a later point in time. (VOY: "Author, Author")
An ability unique to The Doctor, Voyager's EMH was able to leave sickbay or the holodeck and to roam freely with the help of a mobile emitter (originating from 29th century technology). (VOY: "Future's End, Part II") Voyager's EMH was even given the responsibility of commanding the ship as the Emergency Command Hologram (ECH) if the ship's commanding officers were not present, incapacitated, or even dead. (VOY: "Tinker Tenor Doctor Spy", "Workforce", "Workforce, Part II", "Renaissance Man")
When The Doctor was sent in a holographic data stream to contact the USS Prometheus, he found the starship in the hands of Romulans, who had killed the Starfleet crew and captured the ship. The Doctor activated the ship's EMH, a Mark II, to help him recapture the ship, although the Mark II initially preferred to just deactivate and wait for rescue, and then treated The Doctor as inferior despite the latter's vastly superior life experiences. The Doctor ultimately persuaded the Mark II to take action and help him. They planned to disable the Romulans by venting an anesthetic gas, but The Doctor was captured by the Romulans when he attempted to reach the environmental controls on the bridge. During The Doctor's interrogation, the Mark II simulated a bio-hazard, opening the vents which released the gas, knocking out the Romulans. The Doctor and the Mark II successfully fought off Romulan warbirds using the ship's experimental weapons systems, returned the ship into Starfleet's hands, and informing Starfleet that Voyager was in the Delta Quadrant. (VOY: "Message in a Bottle")
The EMH was a holographic simulation of a Human, but with no internal organs beneath the apparent surface to conserve computer power. EMHs were not equipped with reproductive organs. The Doctor, however, wrote additional routines into his holomatrix to facilitate romantic endeavors and has also had several relationships, one of which inexplicably resulted in a son. (VOY: "Message in a Bottle", "Blink of an Eye")
Holodecks used omnidirectional holographic diodes. A sickbay was fitted with a system of OHDs that projected an image of the EMH. Each projected a complete image. Visible portions changed as the hologram moved, creating an illusion of fluid motion.
Magnetic containment fields allowed the EMH to interact with physical objects. These force fields moved as the EMH moved to create the appearance of solid matter. The containment fields could be shut off, allowing objects and people to pass through them – an EMH's cohesion could range from solid to intangible. (VOY: "Phage")
- When OHDs and magnetic field generators were added to other parts of a ship, they allowed the hologram to leave sickbay (as in more advanced Starfleet ships or modified configurations). Without these additional projectors, the EMH could only function in sickbay and the holodeck.
The USS Voyager also discovered the 29th century mobile emitter technology which, when attached to the EMH and its program transferred to emitter, would allow EMH to roam freely on board ship, shuttles or even planetary surfaces. This allowed the EMH to act as a medical aid during away missions. However, damage to the emitter posed a risk of damage or even deletion of the EMH.
When he was first activated, the Voyager EMH apparently did not have the ability to deactivate himself after he finished his duties. However, he was later given that ability by issuing computer command "Override Command 1-EMH-Alpha; End Program". (VOY: "Jetrel") Interestingly, the Mark II apparently had this ability as part of his programming. (VOY: "Message in a Bottle")
- All episodes of Star Trek: Voyager except:
- DS9: "Doctor Bashir, I Presume"
- Star Trek: First Contact
See also Edit
- Long-term Medical Holographic program
- Emergency Command Hologram
- Jupiter Station Diagnostic Program Alpha-11
- "I'm a doctor, not a..." quotes:
In Star Trek Online's Federation tutorial, players encounter a new version of the Emergency Medical Hologram (EMH Mark VI) serving aboard the USS Khitomer. Resembling a Vulcan with silver hair, this EMH, in dialogue released on YouTube but not included in game, claims to have a "personality matrix [that] combines qualities of more than twenty physicians, scientists, and counselors - including Admiral Beverly Crusher of Starfleet Medical, Ambassador Spock, and Gui Ka'Trel of Andoria." He is voiced by Zachary Quinto.  Also in Star Trek Online, Emergency Medical Holograms, alongside the new Emergency Engineering Holograms and Emergency Security Holograms can be acquired as Duty Officers. 
In the game's The Delta Quadrant story arc, players also encounter and work alongside The Doctor in several missions.