Celebrities attending the Met Gala Ball last night in New York - held at the Metropolitan Museum of Art last night - were given strict instructions not to take photos by Vogue magazine's US editor, Anna Wintour.
According to the New York Post newspaper's Page Six column, the editor's note prior to the ball read: "The use of phones for photography and social media will not be permitted inside the gala."
However, Justin Bieber was the first star to defy the rule, posing for a snap with supermodel Cara Delevingne.
It's not a surprise that Kim Kardashian West also posted several snaps to her Instagram account throughout the evening.
She posed with famous faces such as her husband Kanye West, Madonna, Lady Gaga, Cher, Marc Jacobs and Jennifer Lopez, who she described as her "idol".
Madonna also threw caution to the wind by sharing a variety of photos with her 3.7 million Instagram followers, including one with fellow female singers Katy Perry and Lady Gaga.
Captioning the picture, she wrote: "Girls night out.......... Kissing the Ring........Finally!#metball (sic)."
Reposting the shot on her own account, Katy Perry joked: "dropping our single tomorrow #stolethispicfromM#MONSTERCATREBELHEARTS (sic)."