I think Britney needs to go sit in a cage and we throw away the key until she straightens out.
Even if she is not doing ILLICIT substances, she could still be doing prescription drugs, such as hydrocodone and oxycontin.
Im not going to say yay or nay on Dr. Phil being able to 'save' her. Dr. Phil is going to tell her to either put up or shut up. If she wants those kids back, she's going to have to do a complete 180 degree turn.
Personally, I think she should move back to her hometown and live a very low-key life for a year and just use it to get the necessary help she needs. Once she straightens up she needs to then petition to the court to allow supervised visits weekly, then as the court monitors her and sees her improve they may say OK now you can have overnight visitation with the kids every week. But she has to realize no amount of drama or money is going to convince any judge to immediately grant her sole custody of the children. She's going to have to really take that first step and take any help she can get to get her life back on track. And also I would also ban her from living in LA ever again; that town does nothing but destroys her.