The accused conspired to sell the identities of thousands of Puerto Ricans to illegal immigrants, US authorities say.
Legal documents were allegedly sold for as much as $2,500 (£1,631) per person.
Hundreds of birth certificates, Social Security numbers and driver’s licences were bought since 2009, officials say.
A tip-off from police in the US state of Illinois prompted an almost two-year long undercover operation known as Island Express.
The 50 suspects have each been charged with conspiracy to commit identification fraud, which carries a sentence of up to 15 years in prison.
A suspected network of people in several US states are said to have sold legal documents originating in the US island territory of Puerto Rico in the Caribbean as part of the alleged black-market ring.
Puerto Rican documents were especially coveted because they are legitimate US documents with Hispanic names – and many illegal immigrants to the US are originally from Latin American countries.
“The vast majority were legitimate documents obtained by fraudulent or false means,” said Immigration and Customs Enforcement Director John Morton.
“We have gone after everyone involved in the chain: the leaders, the suppliers, the brokers, the runners.”
The alleged conspiracy was kept hidden through a sophisticated code system.
Go-betweens would make coded phone calls asking for skirts for female customers and pants for male customers in specific sizes which referred to the age and type of identity requested, the ICE alleges.
It is alleged that the suppliers even offered to exchange the documents if customers were not satisfied.
In 2010, thousands of Puerto Ricans were reported to have been subject to identity fraud and in July of that year the government began annulling old birth certificates and issuing new ones with added security features in order to address the problem.
It is not known how much money the gang made from the operation.
source: BBC © 201