The United States-based social media platform went down for many users around 21:30 GMT, but service is re-established.
Twitter has expanded its policy barring hateful speech to include “language that dehumanizes people on the basis of race, ethnicity and national origin”.
In a statement, it added that it “will also continue to surface potentially violative content through proactive detection and automation”.
Last year, Twitter banned speech that dehumanises others based on religion or caste and updated the rule in March this year to add age, disability and disease to the list of protected categories.
Civil rights group Color of Change, part of a coalition of advocacy organisations that have been pushing tech companies to reduce hate speech online, called the changes “essential concessions” following years of outside pressure.
A Twitter spokesperson said the company had planned from the start to add new categories to the policy over time after testing to ensure it can consistently enforce updated rules.
Our rules continually evolve to help keep people safe. Today, we’re expanding our hateful conduct policy to address language that dehumanizes people on the basis of race, ethnicity, or national origin.
— Twitter Safety (@TwitterSafety) December 2, 2020
In a statement, Color Of Change Vice President Arisha Hatch criticised Twitter for failing to update the policy before November’s presidential election, despite repeated warnings by the advocacy groups about violent and dehumanising speech.
Hatch also said Twitter has declined to provide transparency into how its content moderators are trained and the efficacy of its artificial intelligence in identifying content that violates the policy.
“The jury is still out for a company with a spotty track record of policy implementation and enforcing its rules with far-right extremist users,” she said. “Void of hard evidence the company will follow through, this announcement will fall into a growing category of too little, too late PR stunt offerings.”