Joint exploration in the West Philippines Sea (South China Sea) with China is in accordance with the 1987 Constitution, Malacañang insisted on Thursday, after President Rodrigo Duterte likened China’s offer of joint exploration to “co-ownership” of the disputed area. In a news conference, Palace spokesman Harry Roque Jr. rejected Supreme Court Senior Associate Justice Antonio Carpio’s claim that Duterte’s idea of joint exploration with China was against the Constitution, which states that only the Philippines can exploit its 200-nautical-mile exclusive economic zone (EEZ). “The existing jurisprudence is, yes we can enter into joint exploration and joint exploitation with foreign entities provided that it complies with the Constitution among others…pursuant to a written agreement signed by the President and submitted to Congress,” Roque told reporters.

Valente, C. S., Reyes, D., & Panti, L. P. (2018, March 2). 'Joint exploration in West PH Sea legal'. The Manila Times, pp. A1, A2.