Economic agreements, such as free trade agreements (FTA) or foreign direct investment (FDI), signed by two states, are a common example of bilateralism. Since most economic agreements are signed according to the specific characteristics of the contracting countries to give preferential treatment to each other, not a generalized principle but a situational differentiation is needed. Thus through bilateralism, states can obtain more tailored agreements and obligations that only apply to particular contracting states. However, the states will face a trade-off because it is more wasteful in transaction costs than the multilateral strategy. In a bilateral strategy, a new contract has to be negotiated for each participant. So it tends to be preferred when transaction costs are low and the member surplus, which corresponds to “producer surplus” in economic terms, is high. Moreover, this will be effective if an influential state wants control over small states from a liberalism perspective, because building a series of bilateral arrangements with small states can increase a state's influence.
There has been a long debate on the merits of bilateralism versus multilateralism. The first rejection of bilateralism came after the First World War when many politicians concluded that the complex pre-war system of bilateral treaties had made war inevitable. This led to the creation of the multilateral League of Nations (which was disbanded in failure after 26 years).
A similar reaction against bilateral trade agreements occurred after the Great Depression, when it was argued that such agreements helped produce a cycle of rising tariffs that deepened the economic downturn. Thus, after the Second World War, the West turned to multilateral agreements such as the General Agreement on Tariffs and Trade (GATT).
Despite the high profile of modern multilateral systems such as the United Nations and World Trade Organization, most diplomacy is still done at the bilateral level. Bilateralism has a flexibility and ease lacking in most compromise-dependent multilateral systems. In addition, disparities in power, resources, money, armament, or technology are more easily exploitable by the stronger side in bilateral diplomacy, which powerful states might consider as a positive aspect of it, compared to the more consensus-driven multilateral form of diplomacy, where the one state-one vote rule applies.
A 2017 study found that bilateral tax treaties, even if intended to "coordinate policies between countries to avoid double taxation and encourage international investment", had the unintended consequence of allowing "multinationals to engage in treaty shopping, states’ fiscal autonomy is limited, and governments tend to maintain lower tax rates."