Britney Spears's deposition is "slow going," and could drag on for multiple sessions, concedes Kevin Federline's lawyer, Mark Vincent Kaplan. Asked if the deposition could last five or more sessions, Kaplan replied, "It wouldn't surprise me." The attorney added, "There are many areas that I have not yet explored." Spears, 26, has been cross examined for a total of one hour over two sessions. (She has been late to both.) As of the second session Monday, Kaplan said he'd only completed "two percent" of his questioning, which Spears must answer while under oath. Spears's first session lasted a mere 14 minutes, and occurred just hours before her infamous Jan. 3 meltdown. The lawyer, who could not reveal specifics, is likely grilling the pop star about past drug and alcohol use, her failure to follow court orders, and anything else that pertains to her parenting. (The questioning lays the groundwork for the Spears-Federline custody trial scheduled for April.) On Thursday, Kaplan also began deposing Spears confidante Sam Lutfi, who had evaded the sit-down for months.