Britney Spears' lawyers will come out of the gate swinging in Sam Lutfi's lawsuit against her and her family ... calling BS on his argument that the singer was on drugs and he was trying to save her.
Sources connected with the case tell us ... lawyers for the conservatorship will scoff at Lutfi from the get-go, noting that he is suing her because he claims she signed a contract making him her manager.
Their point -- how can someone deep into drugs be competent enough to sign any contract, and what's the point of signing a contract if she's too wasted to perform?
Lutfi claims Britney was on meth and other drugs and he worked 24/7 to rehab her, to no avail. Lawyers for Britney and Lynne Spears will make the case that Sam was like a sleazy drug pusher and fame whore who fueled Britney with drugs to control her and isolate her from her friends and family.