How was that not possible before?

This is the best summary I could come up with:

Illinois state representative Jennifer Gong-Gershowitz told the Daily Herald that she introduced the anti-doxxing law as "a way to hold accountable those who perpetuate hate online."

The ADL's ultimate goal is to see a federal anti-doxxing law passed, but right now, Congress is only taking small steps in that direction by mulling the Doxing Threat Assessment Act introduced in May.

ACLU of Illinois' director of communications and public policy, Ed Yohnka, told the Daily Herald that his organization remained opposed because the law could infringe on free speech rights.

“Arming our national security officials and law enforcement with knowledge of how these groups operate and for identifying vulnerabilities and preventing attacks is a first step to protect our communities from harm.”

Since the Doxing Threat Assessment Act was introduced, the number of co-sponsors has doubled, suggesting the bipartisan bill is gaining popular support and has a decent chance of passing.

), said that persecuted religious groups and businesses appeared most vulnerable and "with more information, our law enforcement will be able to develop a more robust approach to the protections of Americans and their data.”

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Seems like a real mixed bag, leaning towards a negative because it requires a civil lawsuit. On one hand sure, good, you can sue harassers at the source. On the other hand how many nasty things like neo-nazi group membership are brought to light through doxxing and will also become illegal. and since it requires you bring suit, this will protect the people with more money/resources more often than not.

Men, doxxing is a valid tactic to use against fascists