The "Unmasking Antifa Act" would provide "penalty enhancements" for persons who threaten or injure others while masked or disguised.
The bill would not make it illegal to join Antifa (or any other group), and the bill has not yet been voted upon, passed, or implemented.
The increased attention focused a Republican-sponsored Congressional bill targeting masked protesters was misrepresented by at least one disreputable website that overstated its implications.
On 12 July 2018, Neon Nettle published an article claiming that Republican congressman Dan Donovan's proposed HR 6054 bill (known as the "Unmasking Antifa Act of 2018") had made it illegal for people to join "Antifa," the catch-all name for various groups who engage in demonstrations against white nationalist and fascist groups:
In reality, the as-yet-unpassed bill, which was introduced to the House of Representatives on 8 June 2018, addresses public behavior (primarily "committing certain offenses while in disguise"), not allegiance or membership with any particular group:
Whoever, whether or not acting under color of law, while in disguise, including while wearing a mask, injures, oppresses, threatens, or intimidates any person in any State, Territory, Commonwealth, Possession, or District in the free exercise or enjoyment of any right or privilege secured to him by the Constitution or laws of the United States, or because of his having so exercised the same, shall be fined under this title, imprisoned not more than 15 years, or both.
Law enforcement officers, however, are not subject to the ban and may cover their faces while performing their duties at protests.
"Americans have the natural right to speak and protest freely; it is not a right to throw Molotov cocktails and beat people who assemble peacefully while hiding behind a mask," Donovan said in defense of the bill on Twitter. "My bill adds a penalty for doing so to the decades-old civil rights statutes."
Americans have the natural right to speak and protest freely; it is not a right to throw Molotov cocktails and beat people who assemble peacefully while hiding behind a mask. My bill adds a penalty for doing so to the decades-old civil rights statutes
— Dan Donovan (@RepDanDonovan) July 11, 2018
Nothing in the bill specifically precludes individuals from joining a group or movement related to Antifa (who sometimes don black clothing and masks), just as it doesn't specifically criminalize joining organizations such as Ku Klux Klan (who are also known for appearing in public wearing identity-obscuring garb). The bill seeks to "provide penalty enhancements" for those who threaten or harm others while masked or disguised, regardless of any group membership.
Moreover, HR 6054 hasn't even yet been brought to a vote yet, much less passed by Congress and signed into law, so asserting (as Neon Nettle did) that any activity referenced in that bill "is now illegal" is putting the cart well before the horse.
"Antifa" is a loose collection of autonomous groups, networks, and individuals, not a discrete, centrally run organization. Anyone can claim to be "antifa," and no authority regulates or controls what various entities calling themselves "antifa" may or may not do. As such, it would be extremely difficult to "ban" anyone from joining something so amorphous in nature.
The Neon Nettle story also injected a common trope among conspiracy theorists by name-dropping George Soros, the Hungarian-American billionaire who has also been accused of funding gun-safety protesters and putting money directly into the hands of protesters against extrajudicial killings by police.
"Antifa" have become a popular scapegoat for various right-wing opponents, who have attempted to link them to mass shooting attacks, falsely accuse them of committing gang-style attacks, or otherwise portray them as being just as prone to violence as white nationalists.
However, political experts have questioned that characterization of "antifa," pointing out that those tagged with that name are far less violent than the right-wing contingents they oppose, as recorded in an Anti-Defamation League report on extremism:
Over the past 10 years (2007-2016), domestic extremists of all kinds have killed at least 372 people in the United States. Of those deaths, approximately 74 percent were at the hands of right-wing extremists, about 24 percent of the victims were killed by domestic Islamic extremists, and the remainder were killed by left-wing extremists.