Nearly 70,000 people are suing the police over being strip-searched for minor offences like fare-dodging.
Constitutionally barred from a third term as mayor, Mr Giuliani, usually known as Rudy, had been considered the Republican Party's best candidate to challenge Hillary Clinton for the post.
That was despite the fact that he is a Republican in a city where they are outnumbered 5-to-1 by Democrats.
But his campaign was dogged not only by health problems, but also by the announcement that he is divorcing his wife of 16 years, Donna Hanover.
However, the New York mayor denied that his decision to quit the race had any connection with his failing marriage.
Ms Hanover, an actress and broadcaster, publicly accused her husband of having had an affair with a former City Hall aide. Mr Giuliani denied that but has acknowledged a relationship with another woman, Judith Nathan.
Zero tolerance blues
Mr Giuliani was returned to office after a landslide victory in January 1998. The former lawyer and state prosecutor has been credited with turning around a city that once seemed ungovernable, particularly in regard to crime.
Overall crime rates have dropped by an astonishing 44% to their lowest in more than a generation, and the city's murder rate is down by 70%.
Mayor Giuliani might claim that his "zero tolerance" policy has brought New York City's crime rate down to record lows, but some New Yorkers have tired of his administration.
Nearly 70,000 people are suing the police over being strip-searched for minor offences like fare-dodging.
And Rudy Giuliani has been accused of confidence to the point of arrogance in taking excess personal credit for the truly remarkable drop in the New York crime rate.
Bullish as ever, Mayor Giuliani adopted a tough defence in the face of the recent legal disputes.
"There are people that are entitled to some degree of compensation for it but they're not entitled to win the lottery over it," he said.
School shocker
Born in 1944 into the third generation of working class Italian immigrants from Brooklyn, Mayor Giuliani is known for his strong work ethic and respect for the law.
But while Mayor Giuliani's record on fighting crime is infamous, he has been criticised on social issues.
He came under fire last year over a proposed voucher system that would allow poor children in New York's worst schools to attend private ones.
Unfortunately, the scheme's merits were buried by a media furore over some of Mr Giuliani's extreme comments on the day he tried to launch it.
The mayor described New York's schools as "dysfunctional" and "just plain terrible".
"The whole system should be blown up," he said, apparently undermining New York's education system for the unlucky millions who would not be awarded vouchers.