Christie’s has postponed its online auction of works by Jean-Michel Basquiat due to a lawsuit filed by the late artist’s sisters last week. The suit disputes the authenticity of many of the available lots, and accuses the auction house of using language in the catalogue that implies that the sale has the approval of the Basquiat estate. Before the Basquiat authentication committee disbanded in 2012, it had only reviewed seven of the approximately 50 items for sale, authenticating six.

A statement on the Christie’s website for the sale announces its postponement, stating “our goal is to allow time for all parties involved to reach an equivalent level of confidence in the validity of these items, so that the sale may resume at a later date.”