Legally Blonde star Selma Blair has undergone a secret rehab stint at the facility Britney Spears checked out of last month (Mar07), according to US reports. Friends tell tabloid the National Enquirer the 34-year-old actress has been struggling with a substance abuse problem that became worse after she split from husband Ahmet Zappa last year (06). Blair reportedly checked into Promises rehab facility in Malibu, California last month (Mar07). One pal tells the publication, "She embraced what she learned at Promises and distinguished herself as a model patient." When WENN went to press with this story, Blair's agent was unavailable for comment.