Britney 2008–10: Conservatorship and Circus

On January 3, 2008, Spears refused to relinquish custody of her sons to Federline's representatives. She was hospitalized at Cedars-Sinai Medical Center, after police that arrived at her house noted she appeared to be under the influence of an illicit substance. The following day, Spears's visitation rights were suspended at an emergency court hearing, and Federline was given sole physical and legal custody of the children. On January 31, 2008, Spears was committed to the psychiatric ward of Ronald Reagan UCLA Medical Center and put on 5150 involuntary psychiatric hold. The court placed her under temporary conservatorship of her father James Spears and attorney Andrew Wallet, giving them complete control of her assets. Spears was released on February 6, 2008. Her parents expressed disappointment and concern at the decision to release her. The following month, she guest-starred on the How I Met Your Mother episode "Ten Sessions" as receptionist Abby. She received positive reviews for her performance, as well as bringing the series its highest ratings ever.In July 2008, Spears regained some visitation rights after coming to an agreement with Federline and his counsel.On September 7, 2008, Spears opened the MTV Video Music Awards with a pre-taped comedy sketch with Jonah Hill and an introduction speech. She won Best Female Video, Best Pop Video and Video of the Year for "Piece of Me". A 60-minute introspective documentary, Britney: For the Record, was produced to chronicle Spears' return to the recording industry. Directed by Phil Griffin, For the Record was entirely shot in Beverly Hills, Hollywood, and New York City during the third quarter of 2008. Main shooting began on September 5, 2008, two days before Spears' appearance at the MTV Video Music Awards. For the Record was broadcast on MTV on November 30, 2008 to 5.6 million viewers for the two airings on the premiere night. MTV reported that Spears' documentary garnered on average, the highest rating in its Sunday night timeslot, in the network's history.

Her sixth studio album Circus, was released in December 2008. It received positive reviews from critics; according to the music review aggregation of Metacritic, it garnered an average score of 64/100. Circus debuted at number one in Canada, Czech Republic and the United States, and inside the top in many European nations. In the United States, Spears became the youngest female artist to have five albums debut at number one, earning a place in the Guinness Book of World Records. She also became the only act in the Soundscan era to have four albums debut with 500,000 or more copies sold. Circus became one of the fastest-selling albums of the year, and has sold 4 million copies worldwide. Its lead single, "Womanizer", became her first number one in the Billboard Hot 100 since "...Baby One More Time" and topped the charts in countries such as Belgium, Canada, Denmark, Finland, France, Norway and Sweden. It was also nominated for a Grammy in the category of Best Dance Recording. In January 2009, Spears and her father James obtained a restraining order against her former manager Sam Lufti, ex-boyfriend Adnan Ghalib and attorney Jon Eardley—all of whom, court documents claim, had been conspiring to gain control of Spears's affairs. The restraining order forbids Lutfi and Ghalib from contacting Spears or coming within 250 yards of her, her property or family members. Spears embarked on The Circus Starring Britney Spears in March 2009. With a gross of U.S. $131.8 million, it became the fifth highest grossing tour of the year.

She released her second greatest hits album, The Singles Collection in November 2009. "3" became her third number one single in the US, and was the first song to debut at the top of the charts in three years. Later that month, she released an application for iPhone and iPod Touch titled "It's Britney!". In May 2010, Spears's representatives confirmed she was dating her agent Jason Trawick, and that they had decided to end their professional relationship to focus on their personal relationship. Spears designed a limited edition clothing line for Candie's, which was released in stores in July 2010. On September 28, 2010, she made a cameo appearance on a Spears-themed tribute episode of American TV show Glee, titled "Britney/Brittany". Spears approved of the episode, although her appearances received mixed reviews from critics. The episode drew Glee's second largest audience, as well as the show's highest ratings ever.

Britney 2004–07: Compilation albums, motherhood, personal struggles and Blackout

On January 3, 2004, Spears married childhood friend Jason Allen Alexander at The Little White Wedding Chapel in Las Vegas, Nevada. The marriage was annulled 55 hours later, stating that Spears "lacked understanding of her actions". She began The Onyx Hotel Tour in support of In the Zone in March 2004. On June 8, 2004, Spears fell and injured her left knee during the music video shoot for "Outrageous". She was taken immediately to a local hospital, where doctors performed an MRI scan and found floating cartilage. The following day, Spears underwent arthroscopic surgery. She was forced to remain six weeks with a thigh brace, followed by eight to twelve weeks of rehabilitation, which caused The Onyx Hotel Tour to be canceled. During 2004, Spears became involved in the Kabbalah Centre through her friendship with Madonna.

In July 2004, she announced her engagement to American dancer Kevin Federline, whom she had met three months before. The romance received intense attention from the media, since Federline had recently broken up with actress Shar Jackson, who was still pregnant with their second child at the time.The initial stages of their relationship were chronicled in Spears's first reality show Britney & Kevin: Chaotic. They held a wedding ceremony on September 18, 2004, but were not legally married until three weeks later on October 6 due to a delay finalizing the couple's prenuptial agreement. Shortly after, she released her first fragrance with Elizabeth Arden, Curious, which broke the company's first-week gross for a perfume. In October 2004, Spears announced she would be taking another career break to start a family. Greatest Hits: My Prerogative, her first greatest hits compilation album, was released in November 2004. Spears's cover version of Bobby Brown's "My Prerogative" was released as the lead single from the album, reaching the top of the charts in Finland, Ireland, Italy and Norway. The second single, "Do Somethin'", was a top ten hit in Australia, the United Kingdom and other countries of mainland Europe. Worldwide, Greatest Hits: My Prerogative sold over 5 million copies. In late 2004, Spears went on KIIS-FM radio in Los Angeles, CA to play a new demo titled "Mona Lisa." The demo was to be the first single from an upcoming album called the "Original Doll." However, Spears' label later cancelled the album for unknown reasons.Spears gave birth to her first child, Sean Preston Federline, on September 14, 2005.

In November 2005, she released her first remix compilation, B in the Mix: The Remixes, which consists of eleven remixes. In February 2006, pictures surfaced of Spears driving with her son Sean, on her lap instead of in a car seat. Child advocates were horrified by the photos of her holding the wheel with one hand and Sean with the other. Spears claimed that the situation happened because of a frightening encounter with paparazzi, and that it was a mistake on her part. The following month, she guest-starred on the Will & Grace episode "Buy, Buy Baby" as closeted lesbian Amber Louise. She publicly announced she no longer studied Kabbalah in June 2006, explaining, "my baby is my religion." Two months later, Spears posed nude for the cover of Harper's Bazaar. The picture was heavily compared to Demi Moore's August 1991 Vanity Fair cover. She gave birth to her second child, Jayden James Federline, on September 12, 2006. On November 7, 2006, Spears filed for divorce from Federline, citing irreconcilable differences. Their divorce was finalized in July 2007, when the couple reached a global settlement and agreed to share joint custody of their children. Spears's aunt Sandra Bridges Covington, with whom she had been very close, died of ovarian cancer in January. On February 16, 2007, Spears stayed in a drug rehabilitation facility in Antigua for less than a day. The following night, she shaved her head with electric clippers at a hair salon in Tarzana, Los Angeles. She admitted herself to other treatment facilities during the following weeks.After completing a month-long program at Promises, she wrote on her website, "I truly hit rock bottom. Till this day I don't think that it was alcohol or depression. [...] was like a bad kid running around with ADD." In May 2007, she produced a series of promotional concerts at House of Blues venues, titled The M+M's Tour. Spears lost physical custody of her children to Federline on October 1, 2007. The reasons of the court ruling were not revealed to the public.

Her fifth studio album, Blackout, was released in October 2007. It debuted at the top of charts in Canada and Ireland, number two in the U.S. Billboard 200,—held off from the top spot by Eagles's Long Road out of Eden— France, Japan, Mexico and the United Kingdom and the top ten in Australia, Korea, New Zealand and many European nations. In the United States, Spears became the only female artist to have her first five studio albums debut at the two top slots of the chart. Blackout sold over 3.1 million copies worldwide. Peter Robinson of The Observer said that "Britney has delivered the best album of her career, raising the bar for modern pop music with an incendiary mix of Timbaland's Shock Value and her own back catalogue." Dennis Lim of Blender commented, "Spears’s fifth studio album is her most consistent, a seamlessly entertaining collection of bright, brash electropop." Blackout won Album of the Year at MTV Europe Music Awards 2008 and was listed as the fifth Best Pop Album of the Decade by The Times. Spears performed the lead single "Gimme More" at the 2007 MTV Video Music Awards. The performance was panned by many critics. David Willis of BBC stated her performance would "go down in the history books as being one of the worst to grace the MTV Awards". Despite the backlash, the single rocketed to worldwide success, peaking at number one in Canada and the top ten in almost every country it charted. The second single "Piece of Me" reached the top of the charts in Ireland and reached the top five in Australia, Canada, Denmark, New Zealand and the United Kingdom. The third single "Break the Ice" was released the following year and had moderate success due to Spears not being able to promote it properly. In December 2007, Spears began a relationship with paparazzo Adnan Ghalib.

Britney 2001–03: Crossroads and In the Zone

In February 2001, Spears signed a $7–8 million promotional deal with Pepsi, and released another book co-written with her mother, entitled A Mother’s Gift. Her third studio album,Britney, was released in November 2001. While on tour, she felt inspired by hip hop artists such as Jay-Z and The Neptunes and wanted to create a record with a funkier sound. The album debuted at number one in the Billboard 200 and reached top five positions in Australia, the United Kingdom and mainland Europe and sold over 12 million copies worldwide. Stephen Thomas Erlewine of Allmusic called Britney "the record where she strives to deepen her persona, making it more adult while still recognizably Britney. [...] It does sound like the work of a star who has now found and refined her voice, resulting in her best record yet." The album was honored with two Grammy nominations—Best Pop Vocal Album and Best Female Pop Vocal Performance for "Overprotected"— and was listed in 2008 as one of Entertainment Weekly's "100 Best Albums from the Past 25 Years". The album's first single, "I'm a Slave 4 U", became a top-ten hit worldwide.

Spears's performance of the single at the 2001 MTV Video Music Awards featured a caged tiger and a large albino python draped over her shoulders. It was harshly received by animal rights organization PETA, who claimed the animals were mistreated and scrapped plans for an anti-fur billboard that was to feature Spears.To support the album, Spears embarked on the Dream Within a Dream Tour. The show was critically praised for its technical innovations, the pièce de résistance being a water screen that pumped two tons of water into the stage. The tour grossed $43.7 million, becoming the second highest grossing tour of 2002 by a female artist, behind Cher's Farewell Tour. Her career success was highlighted by Forbes in 2002, as Spears was ranked the world's most powerful celebrity.Spears also landed her first starring role in Crossroads, released in February 2002. Although the film was largely panned, most critics actually praised Spears's acting. Crossroads, which had a $11 million budget, went on to gross over $57 million worldwide.

In June 2002, Spears opened her first restaurant, Nyla, in New York City, but terminated her relationship in November, citing mismanagement and "management's failure to keep her fully apprised". In July 2002, Spears announced she would take a six month break from her career; however, she went back into the studio in October to record her new album.Spears's relationship with Justin Timberlake ended after three years. In December 2002, Timberlake released the song "Cry Me a River" as the second single from his solo debut album. The music video featured a Spears look-alike and fueled the rumors that she had been unfaithful to him.As a response, Spears wrote the ballad "Everytime" with her backing vocalist and friend Annet Artani. The same year, Limp Bizkit frontman Fred Durst said that he was in a relationship with Spears. However, Spears denied Durst's claims. In a 2009 interview, he explained that "I just guess at the time it was taboo for a guy like me to be associated with a gal like her." Spears opened the 2003 MTV Video Music Awards with Christina Aguilera, performing "Like a Virgin". Halfway through they were joined by Madonna, with whom they both kissed. The incident was highly publicized.

Spears released her fourth studio album, In the Zone, in November 2003. She assumed more creative control by writing and co-producing most of the material. Vibe called it "A supremely confident dance record that also illustrates Spears's development as a songwriter." NPR listed the album as one of "The 50 Most Important Recording of the Decade", adding that "the decade's history of impeccably crafted pop is written on her body of work."In the Zone sold over 609,000 copies in the United States and debuted at the top of the charts, making Spears the first female artist in the SoundScan era to have her first four studio albums to debut at number one. It also debuted at the top of the charts in France and the top ten in Belgium, Denmark, Sweden and the Netherlands. In the Zone sold over 10 million copies worldwide. The album produced the hit singles: "Me Against the Music", a collaboration with Madonna; "Toxic"—which won a Grammy for Best Dance Recording; "Everytime" and "Outrageous".