In 1996 Bhutto's husband was jailed for corruption and accused of murdering her brother. Bhutto was removed from government on corruption charges. She has denied all corruption charges and argues that the investigations are politically motivated. In 1999 a military coup removed Sharif as Prime Minister - look at Bhutto's response at the time from BBC News.
Bhutto's appeal is before the Supreme Court in Pakistan but so far no date has been set for its hearing. It if fails, she faces being banned from office and having her assets seized. Her husband is still in jail in Karachi. Bhutto fears if she returns to Pakistan, she will not be allowed out.