The "Superhuman Registration Act" was a controversial law in the Marvel Comics universe that led to the Civil War crisis, like all laws it was designed for the greater good but was arguably abused by certain individuals and became increasingly oppressive, to the point Captain America himself became a fugitive and championed for its removal: unfortunately Tony Stark/Iron Man and several other heroes supported the act and thus a violent confrontation was inevitable.
Mainstream Civil War
In the New Avengers Special: the Illuminati, Iron Man attempts to persuade his Illuminati colleagues to support the SRA, in order to diffuse it. Iron Man predicts that some superhuman or group of superhumans will eventually make a mistake that will cost hundreds of lives (he specifically mentions the Young Avengers and the Runaways as candidates for causing such a catastrophe). After such an event, he went on to predict, the government would inevitably rush to make an example of someone, or everyone, in the superhuman community by passing legislation that would be even more restrictive or persecutory towards them than the proposed SRA. By supporting the Act before it is passed, he suggests, he and his fellow Illuminati might be able to help avert such possible future tragedies and also, by becoming a part of the process, help moderate the legislation so that it would have the minimum possible negative effect on the superhuman community. However, most of the Illuminati members (except for Reed Richards, who ironically had spoken against the similar proposition made 16 years before flatly reject Stark's proposal, leading to the disbandment of the group.
In the same issue the first part of Iron Man's prediction are shown to be accurate when a conflict between the New Warriors and a group of supervillains ends with a massive explosion which kills hundreds of people, including children attending a nearby school. As depicted in the Civil War crossover and series, the public outcry that follows this event leads the government (with the support of Iron Man and fellow Illuminati member Reed Richards) to quickly enact the Superhuman Registration Act (SHRA), 6 U.S.C. S. 558, which required those with naturally occurring superhuman abilities, super abilities acquired through science or magic (including extraterrestrials and gods), and even non-super powered humans using exotic technology, such as Iron Man, to register as "living weapons of mass destruction." Enactment of the law on the federal level led to various revisions to state criminal codes (such as Chapter 40, Article 120, Section 120 of the New York Penal Code and Section 245(d) of the California Penal Code) in order to allow state and federal coordination in enforcing the law. This leads to a major schism and conflict among the superheroes, with the anti-SHRA side- regarding the Act as a violation of civil liberties- led by Captain America and the pro-SHRA side- seeing the Act as a natural evolution of the superhuman's role in the modern world to regain public trust- led by Iron Man. Eventually, Iron Man's side wins the conflict and the "Fifty State Initiative" is established.
Other countries followed America's lead and introduced their own Superhuman Registration laws.
Following the Skrull invasion and the subsequent fall from grace of Iron Man, w:c:villains:Norman Osborn seizes control of the Initiative and SHIELD, but is prevented from getting his hand on the register (and thus the identities of most of the superhuman community) by Tony Stark when he infects the US government database with a computer virus. There is only one copy of the SHRA database, in Stark's brain, where he deleted it, piece by piece, before Osborn could get his hands on it, ironically destroying the very information that was the focus of "Civil War" in the first place.
At the conclusion of Siege, Steve Rogers is named the new head of security of the United States and as a condition of joining, he convinces the government to repeal the Act, allowing superheroes to return to their prior activities.
Ultimate Alliance variant
Although no Registration Act exists in the Ultimate Marvel Universe, there are several laws in place that prohibit superhuman activity. Genetic modification of a human being is illegal, and the Superhuman Test Ban Treaty makes it illegal for nations to employ superhumans. This makes the Test Ban Treaty the polar opposite of the SHRA. In Ultimate Six# 1, it was stated that the law on deliberately created superhumans is still unclear, allowing Nick Fury to hold supervillains indefinitely without any trial and in hidden locations (#5 showed that the President of the United States was unaware of this, and was furious when he learned of it).
The events of the first X-Men film are precipitated when Senator Robert Kelly introduces a Mutant Registration Act to the Senate. This motivates Magneto, who sees such legislation as persecutory towards mutants, to kidnap Kelly and replace him with Mystique, who while impersonating Kelly, withdraws his advocacy for the Act.
In the sequel, X2, the Mutant Registration Act is briefly mentioned when Storm speculates that Nightcrawler's attack on the White House might lead the government to reintroduce the legislation.
X-Men: The Animated Series
The first episode of the 1992 X-Men Animated Series (Night of the Sentinels (part 1); original airdate: 31 October 1992) mentions that some form of registration is in effect already. In the episode, Jubilee's foster parents worry that they may have to "register her with the Mutant Control Agency" after she manifests her powers for the first time.
But following the attack on Jubilee at a mall, it was revealed that the hidden agenda of Henry Peter Gyrich, the founder of the agency is to deceive the mutants into revealing their identities so the Sentinels could eliminate them due to Gyrich's beliefs that mutants pose a threat to society. After the destruction of their files, following the X-Men's raid on the agency, the President decides to cancel the registration act. The government's persecution of mutants is a consistent theme throughout the fifth season of the series.
Marvel Cinematic Universe
In this interpretation, secret identities do not exist, so it's more about government supervision of superhumans. This Registration Act is meant to start and end the entire plot of Captain America: Civil War in 2016 (and is most likely brought about by events in Avengers: Age of Ultron) and Tony Stark is the main antagonist, due to supporting the movement like in the mainstream comics. The MCU version of the Superhuman Registration Act is called the Sokovia Accords and it was formed in the aftermath of an Avengers operation in Lagos, Nigeria which resulted in the accidental deaths of over 11 Wakandan relief workers and many more civilians.
The Avengers: Earth's Mightiest Heroes
Maria Hill claims that all superheroes who save people or possessing of powers are to be recorded to the Superhuman Registration Act. Even after Maria saves the life of Tony Stark and he thanked her, she will not change your mind on the Superhuman Registration Act, she thinks it's Tony Stark that the Avengers could endanger people. Then, Tony proposes a dinner to Maria.
- The Act has mainly been used against the X-Men, due to them being mutants and mutants not being trusted for their powers and threats.
- There have been several versions of the Superhuman Registration Act in alternate media. Some are direct mimics, while others are just parodies:
- In Powers, a Registration Act was made so that superheroes would only be allowed to do their duties if they registered. Many retired because of this.
- In The Incredibles, a parody of the National Security Agency called the National Supers Agency put forth a Superhuman Relocation Program (a parody of witness protection programs) that got superheroes to either stay normal people and work typical jobs, or "go away". This was caused by several incidents around the world where superheroes had caused thousands of dollars worth of property damage and medical bills to go right down the drain (one such incident being Mr. Incredible trying to stop a train from falling off an exploded track, but had damaged the rails and left the train hanging off the tracks, as well as many people in the train getting broken bones and hatred for Mr. Incredible and the El Train Accident as they called it).
- In the DC Comics television series Smallville, the Vigilante Registrations Act (VRA) is proposed legislation that would require vigilantes to register themselves. Led by General Slade Wilson, the VRA forces registered heroes to unmask and officially work for the government or be branded as terrorists. Despite the efforts of Darkseid and his minions to encourage anti-hero propaganda, the actions of the Justice League, Oliver Queen, and the pro-vigilante Senator Martha Kent - ironically aided by an assassination attempt arranged against Martha by the Earth-2 Lionel Luthor, which was based around his personal grudges against her rather than the VRA- result in the Act being repealed and the heroes being permitted to return to their daily lives.
- Due to the Superhuman Registration Act, Iron Man had become evil, supporting the act to the point that he was truly considered a villain.