Article 38(1) of the Statute of the International Court of Justice is generally regarded as setting out the sources of international law. International treaties and conventions is one of the sources of international law in terms of that Article. According to the 1969 Vienna Convention on the law of treaties; part 1, Article 2 on the use of terms- defines the term “treaty” as an international agreement concluded between States in written form and governed by international law, whether embodied in a single instrument or in two or more related instruments and whatever its particular designation. It also includes international agreements involving international organizations as parties. In order to speak of a “treaty” in the generic sense, an instrument has to meet various criteria- first of all, it has to be a binding instrument, which means that the contracting parties intended to create legal rights and duties. Secondly, the instrument must be concluded by states or international organizations with treaty-making power; thirdly, it has to be governed by international law and finally the engagement has to be in writing.
Convention as a generic term according to Article 38 (1) (a) of the Statute of the International Court of Justice refers to “international conventions, whether general or particular” as a source of law, apart from international customary rules and general principles of international law and- as a secondary source- judicial decisions and the teachings of the most highly qualified publicists. This generic use of the term “convention” embraces all international agreements, in the same way as does the generic term “treaty”. The generic term “convention” thus is synonymous with the generic term “treaty”. Convention as a specific term is generally used for formal multilateral treaties with a broad number of parties; they are normally open for participation by the international community as a whole, or by a large number of states. Usually the instruments negotiated under auspices of an international organization are entitled conventions. An example of a Convention is the Convention on the Rights of the Child, which was adopted by the General Assembly of the United Nations on 28 November 1989. This Convention reaffirms the fact that children because of their vulnerability need special care and protection. Article 2 of this Convention states that all rights apply to all children without exception and that it is the State’s obligation to protect children from any form of discrimination and to take positive action to promote their rights. Article 28 talks about the right a child has to education and that it is the State’s duty to ensure that primary education is free and compulsory. This convention also applies to Namibia and the Namibian Constitution is also in conformity with the provisions of the Convention on the Rights of the Child.

A treaty is an agreement in written form between nation-states (or international agencies, such as the United nations, that have been given treaty-making capacity by the states that created them) that is intended to establish a relationship governed by International law. It may be contained in a single instrument or in two or more related instruments such as an exchange of diplomatic notes. Various terms have been used for such an agreement, including treaty, convention, protocol, declaration, charter, Covenant, pact, act, statute, exchange of notes, agreement, modus vivendi ("manner of living" or practical compromise), and understanding. The particular designation does not affect the agreement's legal character.
Traditionally, international law required treaties to be ratified in the same form by all parties. Consequently, reservations or amendments proposed by one party had to be accepted by all. Because of the large number of participating states, this unanimity rule has proved difficult to enforce in modern multilateral treaties sponsored by international agencies for the purpose of creating legal regimes or codifying rules of international law. Where agreement exists on the essential elements of a treaty, international law increasingly is allowing reservations as to minor points not unanimously accepted. Treaties for which ratification is specified come into effect upon the exchange of ratifications between the parties or upon deposit of the ratifications with a designated party or international agency, such as the Secretariat of the United Nations.
A treaty may be terminated in accordance with specifications in the treaty or by consent of the parties. War between the parties does not invariably terminate treaties, as some treaties are made to regulate the conduct of hostilities and treatment of prisoners. Other treaties may be suspended for the duration of the hostilities and then resumed. An unjustified, unilateral abrogation of a treaty may give rise to possible international claims for any injury suffered by the other parties.
Three Main Types of Treaties
There are three important types or classes of treaties. The first is the general multilateral treaty. This type of treaty is one that is open to all states of the world (or if it’s a regional multilateral treaty, opens to all states in the large regional group). The critical role of the multilateral treaty is to lay down rules of behavior (laws) that tend to be of a fundamental and “norm-creating” character. In other words, many of the principles and rules that make up multilateral treaties also form the basis of general rules of law.

Another important class of treaties is those that establish a collaborative mechanism by which states can regulate or manage a particular activity. These treaties tend to lay out a specific purpose or objective and then back it up with legal principles. Collaborative mechanism treaties usually operate through decisions made by their main organs and central governing bodies. They tend to have an institutional and administrative character that allows them to oversee various areas of activity.
The third important class of treaty is the bilateral treaty. These treaties are those made between a small number of states (not necessarily just two, but generally less than four or five). Bilateral treaties often are drafted in contractual terms in which the parties mutually exchange rights and obligations. They are usually detailed and provide for specific conditions that dictate the parties’ rights and duties. Common examples of this type of treaty include treaties of alliance, trade, friendship, etc.

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[ 1 ]. 1969 VIENNA CONVENTION ON THE LAW OF TREATIES.
[ 2 ]. www.United Nations Treaty Collection.com.
[ 3 ]. ibid
[ 4 ]. Ibid
[ 5 ]. www.United Nations Treaty Collection.com.
[ 6 ]. ibid
[ 7 ]. ibid
[ 8 ]. ibid
[ 9 ]. 1989 CONVENTION ON THE RIGHTS OF THE CHILD.
[ 10 ]. ibid
[ 11 ]. ibid
[ 12 ]. The free dictionary. Farlex
[ 13 ]. International human rights instruments.
[ 14 ]. The free dictionary. Farlex
[ 15 ]. Wikipedia. List of treaties