Critics have often accused Opus Dei of intense secrecy. Due to its secrecy critics such as the Jesuit Wladimir Ledóchowski sometimes refer to Opus Dei as a "Catholic", "christian", or "white" form of Freemasonry. Opus Dei does not publish memberships lists, and members generally do not publicly reveal they are part of the organization. . According to its 1950 constitution, members are forbidden to reveal their membership without the express permission of their superiors. This practice has led to rampant speculation about who may or may not be a member of Opus Dei. The 1950 constitution similarly prohibited even revealing how many people were members of Opus Dei.