Twitter community adds a context note to Joe Biden tweet:  President Joe Biden's official Twitter account tweeted, “I make no apologies for being the most pro-union president in American history.”  Twitter added a label to the post that read "Readers added context they thought people might want to know.” The added context read "On December 22, 2022, President Biden signed a bill to block the railroad union from striking." The context note also included a link to a Reuters article to support the note. The label is part of Twitter’s Community Notes system. Twitter users are able to sign up as contributors to add context to tweets.