The Space Corps are the military force, including marines and fleets, which deal with conflicts and peacekeeping away from Earth. The main force depicted is Mega-City One's. Foreign Space Corps have been mentioned and shown: Sino-Cit in "The Corps" (who have an alliance and co-administered forts with the Klegg Empire) and Latin American and "Asian Union conscripts" in Warzone, the latter involving an international coalition.
The look of the Corps is entirely dependant on the artist.
Mega-City One's Corps have appeared in several stories, most notably Judge Dredd: Mandroid and its sequel, Warzone, spinoff The Corps, and Debris. They are unlicensed to act against citizens in Mega-City One (Chaos Day riots being the rare exception) and the strategic interests of the city come above the interests of individual colonies, who may be abandoned to alien attack.
When Space Corps soldiers are severely wounded, they will sometimes be turned into cyborgs: nicknamed "Mandroids", they are highly powerful and designed solely for combat.
They have been primarily shown fighting alien menaces off-world, starting with the Klegg Empire in "The Corps". Warzone showed them being used as an occupying force on a colony planet to prevent it gaining independence, constantly fighting against local insurgent groups.
The Space Corps was operating by at least the 2070s.
In 2109, there were heavy losses in a colony war (not on a MC-1 colony) and citizens were ordered to give blood.
The Corps fought the Klegg Empire across a dozen worlds in th Outer Spiral Arm in the 2110s, under the command of Colony Troop Leader Keitel in the JDSS Solomon, and by early 2116 they'd lost almost 250,000 men with barely any gain. Shortly after Hadrian Volt became Chief Judge, the Corps were ordered to start a Sino-Cit/Klegg war through a false flag attack but the operation was a failure.
The Corps ran a genetically modified soldier program in the 22nd century: soldiers were grown in tubes and indoctrinated, similar to Judges (and especially Black Ops Division but with animal DNA included to enhance them. The program was experimental and one trooper, Armon Gill, tried to eat a civilian.  He was dishonourably discharged in 2122, after twelve years service. This was separate to the Genetic Infantry soldiers, who could be transferred to Space Corps.
Dredd's clone Dolman joined the Space Corps in 2126 but left after 2134.
In 2128, an international coalition was trying to stop the insurgency on colony world New Sylvania. Many foreign forces sent conscripts and dregs, while the MC-1 Corps were ill-disciplined; the bitter troops nicknamed this "the Forgotten War", as nobody back home wanted to know about Space Corps fighting humans. Sergeant Duke, head of a Mandroid squad, told Dredd it was inevitable the planet would get independence. General Agers was revealed to be taking bribes from the insurgents and arrested by Dredd. After Day of Chaos, Space Corps soldiers were recalled to Mega-City One to make up for the amount of dead Judges. However, in their first mission Colonel Lynn Easter tried to airstrike a dissident city block in a fit of pique and were forced by Dolman to call it off. When news of this got out, the citizens no longer trusted or respected the Corps - and under judicial command, they were forced to hold back on lethal force. The Corps openly saw the Judges as weak.
The alien Zhind raided MC-1 colonies and had small scale conflicts for years. When K Alpha 61 was invaded, the Space Corps did not respond due to the political risk of causing a large-scale conflict with the Zhind.
In April 2136, a crack team of marines was sent under Dredd's command to Titan; during planning, Chief Judge Hershey remarked that the city no longer had the ability to send large forces and Aimee Nixon taunted Hershey that the bulk of their space forces were tied up with ex-Colony Marshall Karel Luther's insurgency, which was seeing apes, mutants, and robots rebelling against Mega-City control and establish independent worlds. Ironically, Luther's driving motive was K Alpha 61 being abandoned.
In 2138 the Zhind launched an all-out invasion of human space across the trilateral line. The Space Corps and other MC-1 military forces had to team up with Luther's insurgents to have the edge. The Corps fought a sixteen-week war against the Zhind, with six major engagements and several minor ones like the planet Malfaize; most of these were fleet battles, including a significant battle at Wolfenstar 77154, but the crucial battle was a land engagement at 43 Rega to stop the aliens reaching the Inner Colonies and the solar system. After the insurgents had broken the Zhind at the Battle of 43 Rega, the Special Judicial Squad's space fleet turned and massacred them.
(It's unclear if foreign Space Corps were involved in the Xhind War as well.)
In 2140, a squad of veteran Marines under the psi Rafael "Rafe" Sabitini was dispatched to the colony world Dominion to stop the Dark Judges. Unfortunately, Sabitini had been traumatised at the battle on Malfaize and his decision to execute wounded soldiers - this left him open to contact from the Sisters of Death and he smuggled Judge Fear on board. The Marines found Fear and a transformed Sabitini, Judge Whisper, manifest before they reached Dominion. 
The idea of offworld soldiers had been mentioned in 1980s strips, as part of the planning for an aborted Judge Dredd Fortnightly. This comic would have had a spinoff called B.A.D. Company - a sci-fi update of Wagner's old Darkie's Mob. (This was later picked up and drastically revamped by Peter Milligan, though the first part in Prog 500 would follow the basic plot of Wagner's draft) In this, civilians had joined the 1st Mega-City Volunteers to fight the Colony Wars. Former Titan inmate Kano was put in charge of a colony "wipe-out unit", Battalion Assault Deployment Company, that operated permanently behind enemy lines.
The concept was first named and fleshed out in a published strip by Garth Ennis in 1994, as "the Corps", "the military arm of Mega-City 1's Justice Dept". This was written at the request of editor Alan McKenzie, who wanted a war story featuring space Judges; Ennis lost interest after the strip was partially rewritten by an uncredited figure. As The Corps has the characters trying to undermine the Sino-Cit/Klegg alliance, it may have been part of McKenzie's push for a storyline (later dropped) where Mega-City One and Sino-Cit would go to war. Coincidentally, The Corps came out at the same time as a long-delayed, similar strip called Maelstrom, which featured another team of similarly-armoured soldiers called "STAR Judges" (Special Target Attack Retaliation) and also had art by Colin MacNeil.
Both strips had their military forces established as Judges - the Corps' Special Squads were pulled out of the Academy of Law at ages 3–6 after showing abnormal levels of violence, and trained solely to kill. While not stated in the strip itself, the 'Background' pages for Maelstrom stated that the STAR Judges were "a united space force composed of Judges from different Mega-Cities" - characters were from MC-1, Brit-Cit, Euro-City, and Texas City, with Hondo technology. They operated out of the satellite Justice Matrix, which controlled "Justice System, the judicial forces that patrol Earth's offworld colonies", as well as having operating as a conquering military force offworld.
In the later, post-McKenzie stories under John Wagner (renaming them "Space Corps") and Michael Carroll, the organisation are not Judges but instead drafted from the civilian population. Military veteran characters would be presented as former Space Corps soldiers. The STAR Judges have been ignored.
- ↑ #240, "Warzone" page 2
- ↑ 45th Infantry mentioned in "Spooks", progs 1058-61
- ↑ Prog 1795
- ↑ Megazine 334
- ↑ Part 1 of The Corps
- ↑ 2000 AD #1453-1464
- ↑ 2000 AD #1555-1566
- ↑ Megazine #240-3
- ↑ #1792-6
- ↑ Prog 1779
- ↑ Judge Dredd Megazine #334: "Insurrection III Part 1"
- ↑ Year One: City Fathers
- ↑ Prog 519
- ↑ Prog 918-9
- ↑ Prog 923
- ↑ Prog 1263 and 1342
- ↑ Prog 1247: discharged "last year"
- ↑ Megazine 240, prog 1317
- ↑ Megazine 240-3
- ↑ Prog 1793-6
- ↑ Prog 1801-2
- ↑ Megazine 240
- ↑ Megazine 310
- ↑ Prog 1863: "Titan Part One"
- ↑ Insurrection and Insurrection II
- ↑ Megazine's recap segment for Insurrection III stated it was 2135 but the beginning takes place simultaneously with the end of Insurrection II, which was recapped as 2133; the strip itself never mentioned years and Abnett said in the "Insurrection: Liberty" trade that he saw this strip as being in Dredd's future. Aimee Nixon refers to the "Luther rebellion" in the colonies in Titan, set 2136, and the 2138-set Megazine #373 referred to the Zhind War in the past tense. "Dark Judges: The Torture Garden" gave the year specifically was "2128", a typo for 2138
- ↑ Judge Dredd Megazine #340-2: "Insurrection III"
- ↑ Megazine 405
- ↑ Judge Dredd Megazine #340-2: "Insurrection III"
- ↑ Dark Judges: The Torture Garden
- ↑ Thrill-Power Overload! by David Bishop
- ↑ Reprinted in Megazine 4.15
- ↑ Prog 919, "The Corps Part 2"
- ↑ Thrill-Power Overload! by David Bishop (page 178)
- ↑ Thrill-Power Overload! by David Bishop (page 164)
- ↑ Megazine #239: "15 Years, Creep! Part 4": the strip had waited a year "for the right artist"
- ↑ Prog 919, "The Corps Part 2"
- ↑ Megazine vol.2 #75