On 16 December 2015, the Supreme Court of India mandated several restrictions on Delhi's transportation system to curb pollution. Among the measures, the court ordered to stop registrations of diesel cars and sport utility vehicles with an engine capacity of 2,000 cc and over until 31 March 2016. The court also ordered all taxis in the Delhi region to switch to compressed natural gas by 1 March 2016. Transportation vehicles that are more than 10 years old were banned from entering the capital.