Ms. Spears’s team presents her onstage as fully in control, and backstage, as the mastermind of her show, an artist in top form. But that view seems at odds with the conclusions routinely drawn about her at probate court in Los Angeles, where an undisclosed mental illness and substance abuse led her family to take action in 2008.

Since then, Ms. Spears’s life has been controlled by a court-approved conservatorship, known in other states as a guardianship, designed for people who cannot take care of themselves.

According to the arrangement, which is typically used to protect the old, the mentally disabled or the extremely ill, Ms. Spears cannot make key decisions, personal or financial, without the approval of her conservators: her father, Jamie Spears, and a lawyer, Andrew M. Wallet. Her most mundane purchases, from a drink at Starbucks to a song on iTunes, are tracked in court documents as part of the plan to safeguard the great fortune she has earned but does not ultimately control.

While the conservators are widely credited with rescuing Ms. Spears’s career — and her life — her apparent stability and success could belie the need for continuing restrictions.

There are recent signs, in fact, that the conservators are now acknowledging the great progress she has made. After successfully fighting to keep her from testifying in at least three prior lawsuits — (a probate judge had previously agreed that doing so could cause her “irreparable harm”) — Ms. Spears’s conservators allowed her to testify on Monday in a case filed against her by a former self-described manager. They agreed that “giving such testimony is not likely to cause harm to her,” according to court papers.