The Latino leaders called the anti-loitering law an attempt to criminalize "standing while Latino."
The Court will also hear arguments on the validity of an anti-loitering law enacted by Chicago to combat street gangs.
In private practice, Mr. Estrada defended anti-loitering laws that civil rights and groups have attacked as racist.
Chicago's anti-loitering law, a model for cities seeking to reclaim the streets from violent gangs, was declared unconstitutional.
In addition, he said, the Court has rejected a number of anti-loitering laws for infringing on the right to associate.
But, citing anti-loitering laws, it flatly excluded beggars.
And Chicago instituted an anti-loitering law authorizing arrests of suspected gang members who defy police orders to leave a street.
An anti-loitering law that allowed the Chicago police to arrest more than 42,000 people from 1992 to 1995 was declared unconstitutional last week by the Supreme Court.
The Port Authority bans soliciting for any purpose without a permit, but did not grant permits for begging, citing the anti-loitering law.
Answering one about Grand Central Terminal, he bemoaned the fact that the state's highest court had struck down an anti-loitering law.