The term "soft law" refers to legal instruments which do not have any legally binding force, or whose binding force is somewhat "weaker" than the binding force of traditional law. These are generally, instruments that are not treaties that oblige the stakeholders to follow them, but they have within them ‘norms’ that are believed to b good and therefore need universal application.
The Universal Declaration of Human Rights is also officially termed as a soft law since it was passed by the UN General Assembly as a Declaration and within itself has not given any means where the stakeholders are legally bound to abide by the articles or to enforce them. The preamble of the declaration says that the UDHR is “a common standard of achievement for all peoples and all nations” and the nations must themselves strive to achieve this standard.
While not a treaty itself, the Declaration was openly adopted for the purpose of defining the meaning of the words "fundamental freedoms" and "human rights" appearing in the United Nations Charter. For this reason, the Universal Declaration can be termed as a fundamental constitutive document of the United Nations. Since the UN charter is binding on all member states (according to Section 1, Article 4 in Chapter 2 of the UN charter), most people argue that the Universal Declaration of Human Rights although a soft law, by proxy has a legal binding effect on the nations.
Historically, there are two main sources of international law: treaties and customary law. There have been arguments that soft law has become a third source of