New York City taxi drivers Monday began their second strike of the year to protest GPS requirements and mandatory credit card machines in cabs.

The latest boycott is part of an ongoing effort among some New York City taxi drivers to organize.

The drivers say that New York City's new GPS requirements violate their privacy. City leaders claim it will not and that drivers shouldn't have an expectation of privacy while working in a highly-regulated industry. They instituted rules that require all cabs to have GPS and credit card machines to pass their next vehicle inspections. The New York Taxi & Limousine Commission (TLC) said that the technology will improve efficiency, provide a system for emergency notification, and help passengers recover lost property more easily.

TLC commissioner Matthew W. Daus said that improvements and fare increases "have allowed drivers to benefit from participation in the strongest and most viable taxi industry of its century-long history."

"Experience shows that most drivers appreciate this, and will show their appreciation by doing what they do best and serving the riding public," he said in a prepared statement. "As before, we will have a contingency plan to maximize these drivers' efforts, which will be particularly helpful given the fact that Mondays are traditionally among the slowest days for taxicab leasing."

Many yellow cabs already have the credit card machines, touch-screen video monitors displaying local news and information, and GPS.

New York's cab drivers are considered independent contractors, but some are trying to organize a labor union through the New York Taxi Workers Alliance, which claims to represent more than 8,400 of the city's 44,000 licensed cab drivers.

The last time they went on strike, passengers complained that the drivers who stayed on the road overcharged.

During both strikes, drivers have been allowed to pick up multiple passengers and charge special rates, based on a $10 initial fee and $5 for each zone after that.

Mayor Michael Bloomberg announced Monday that any driver charging or attempting to charge fares in excess of those authorized by the TLC will be prosecuted.

Passengers can report complaints and get updated information through the city's 311 information service or through the city's Web site.

New York State Federation of Taxi Drivers, which claims to represent 10,000 taxi drivers, opposes the strikes.