9 In the case of Rosendo De Borja v. Pinalakas na Ugnayan ng Maliit na Mangingisda sa Luzon et al., G.R. No. 185320,41 the commercial fishing operator asked the SC to construe and declare his rights under Section 4 (58) of RA No. 8550. The petitioner also asked the SC to determine the reckoning point of the 15-kilometer range of municipal waters provided under Section 4 (58), in relation to Rule 4.1 (a) of its Implementing Rules and Regulations (IRR). 42 According to Atty. Espenilla, the petitioner wanted to know how to determine the “general coastline” because it would appear easy enough if the reckoning point were only from the mainland at low tide. However, the issue arises when the municipality is archipelagic since it would not be clear whether those outer islands themselves would generate their own 15 kilometer coastline.43 Otherwise said, the 15-kilometer range of the municipal waters of an archipelagic municipality should be reckoned not only from the coastline of the mainland but also from the coastline/s of the island/s of that municipality, and such coastline/s of the island/s being part and parcel of the general coastline of that municipality. NAMRIA, the agency designated to chart navigational lines and delineate municipal waters under Section 123 of RA No. 8550, was initially guided by the Department of Environment and Natural Resources (DENR) Administrative Order 17 series of 2001 (DAO 17). DAO 17 adopted the Archipelagic Principle44 in delineating municipal waters with offshore islands.45 Archipelagic Principle provides that waters between the mainland and the offshore island, still form part of the 15 kilometers municipal water, and that the offshore island’s coastline form part of the general coastline of the municipality. From there, another point 15 kilometers of municipal water shall be reckoned, as illustrated in Figure 2.46 Figure 2. Archipelagic Principle illustrated (UP-IMLOS) 41 Rosendo De Borja v. Pinalakas na Ugnayan ng Maliit na Mangingisda sa Luzon et al. GR no. 18320, file 19 April 2017, available from www.chanrobles.com/cralaw/2017aprildecisions.php?id=263 42 Additional Terms. Coastline refers to the outline of the mainland shore touching the sea at mean lower tide. www.bfar.da.gov.ph/files/img/photos/IRRofRA10654.pdf (last viewed 11/15/2021) 43 Presentation of UP-IMLOS, supra note 40 44 The Archipelagic Principle is tied to the Philippine Constitution. Part of Article 1 states that “The waters around between, the connecting islands of the archipelago, regardless of their breadth and dimensions, form part of the internal waters of the Philippines.” 45 DENR Administrative Order 17-2001 Section 5(B-c), available from mgb.gov.ph/images/stories/DAO_2001-17.pdf 46 The left-side picture illustrates the difference in municipal water delineation when applying the archipelagic principle (image B) versus not applying it (image A). The right-side picture illustrates the same point but adds what would happen if the principle is not applied for municipalities facing each other between waters.