The official PhilippineTreaty Series was published from vol 1-9 (1944-1983). It is available electronically on HEIN Online (UniMelb staff & students). There has been no official treaty series since 1983.
Philippine Treaties Online - on the official Office of Legal Affairs, Department of Foreign Affairs website. This database provides a list of all bilateral treaties, from 1947 to current, which can be sorted by Title, Category, Date of Signature, Date of Entry into Force, and Contracting Party. Treaties can also be searched by, for example contracting party, topic, and date of entry into force.
The Philippines Supreme Court E-Library contains:
United Nations Treaty Series (UNTS) - includes multilateral and bilateral treaties deposited with the Secretary - General of the UN. This is the most comprehensive online collection of Philippines treaties - containing over 1000 treaties, from 1919 to current, from both the UNTS and its precursor, the League of Nations Treaty Series (LNTS). Treaties are listed, and can be sorted by Registration Number, Title, Participants. Conclusion Date, Date of Entry into Force, and Treaty Type. It can also be searched. To see all treaties to which the Philippines is a party, from the search page, select Participant Search and then select Philippines from the menu.
Clicking on a treaty provides status and ratification information etc and full-text treaties in the UNTS, together with the UNTS citation.
The Consolidated Treaty Series (CTS) (1648-1919) contains two bilateral treaties entered into by the US when the Philippines was under US colonial rule. The CTS has been reproduced in the online Oxford Historical Treaties. From the home page, use the + buttons in the left-hand menu under the Treaty Party heading > Geographic Regions > Asia > Colonial Polities > Philippine Islands (United States).
See also:
Philippine Treaties Index, 1946-2010 by Treaties Adherence
The Rule of Law in Armed Conflict (RULAC) Project website includes information on the international human rights and humanitarian treaties and regional treaties to which the Philippines is a party. The website notes that 'With the exceptions of Additional Protocol I, the Hague Convention and Protocol, the Phillipines are party to all major international humanitarian and human rights law treaties. Furthermore, the Philippines have not made any reservations to those treaties'.
Article II s 2 of the Philippines Constitution provides for the 'incorporation' of the norms and principles of international law by stating ‘[t]he Philippines . . . adopts the generally accepted principles of international law as part of the law of the land.’ The effect of the incorporation clause is that international law automatically becomes Philippine law. Deemed incorporated into Philippine law by the incorporation clause are (1) customary international norms or international custom, and (2) general principles of law.
In contrast, treaties must be 'transformed' into national law in order to become part of the 'law of the land'. This is done:
In the hierarchy of rules in the Philippine legal system, a treaty, once it becomes part of the 'law of the land', has equal status to Acts of Congress.
A treaty may be invalidated if it conflicts with the Constitution or an Act of Congress (Gonzales v Hechanova 9 SCRA 230 (1963))
A treaty is subject to qualification or amendment by a subsequent law (Lao Ichong v Hernandez 101 Phil 1156 (1957)). Conversly, a statute may be amended or qualified by a later treaty.
Source: International Encyclopaedia of Laws: Constitutional Law - the Philippines, Part 1: Sources of Constitutional Law, Chapter 1: Treaties, §2 Hierarchy, 33-34.
If a treaty is included in a treaty series, the treaty series should be cited rather than eg: the UN document number. Treaties are often included in several treaty series. According to Chapter 7.4 (pp 125-127) of the Australian Guide to Legal Citation, treaties should be cited in the following preferential order:
1. Consolidated Treaty Series (ConTS) 1648-1919; League of Nations Treaty Series (LNTS) 1920-1944; or United Nations Treaty Series (UNTS) 1946+
2. An official treaty series of a state party - for the Philippines, this is the Philippine Treaty Series (PTS).
3. International Legal Materials (ILM) (UniMelb staff & student access). This series is on HEIN Online in the Law Journal Library collection (vol 1, 1962+) and in JSTOR (vol 1, 1962+) . This is not a treaty series - but it includes treaty texts and useful introductory information about the treaties, and it is an accepted method of citation. Note that JSTOR's holdings are more up to date than HEIN.
4. If the treaty is not included in any of the above, use the official document number (such as a UN document number) to identify it, using the accepted style as described in Chapter 8 of ACLC.