Let's start by defining international trade law. As the name implies, international trade law refers to the way commerce between countries is conducted and the laws that must be followed. This can include areas like copyright law, environmental protection, labor law, and tariffs (taxes on imports).
When two countries trade, they must agree on a set of rules because each country cannot, by itself, apply its own law. For example, the United States cannot, on its own, tell Austria how to conduct business. But the two countries can agree on standards and laws that they will follow when trading with each other. So, an advantage of international trade law is that both parties, or all parties (since trade can involve multiple countries), have agreed upon a set of rules that every country must follow. For example, ten countries can agree not to trade in ivory or can agree that any cars produced must be made in a way that is environmentally friendly.
The disadvantage of international trade is that each country is going to have to make concessions that may not align with their own country's preferences and laws. For example, US copyright law may be very different than the copyright laws of Honduras or Sweden. US corporations may oppose having to follow different sets of laws depending on where their products are being sold. On the other hand, international trade law can be set in such a way to allow for corporations to have one set of rules, no matter what country they are selling or buying from.
In summary, international trade law can set uniform rules to encourage and standardize trade. These rules and laws can also cause problems, especially when they differ from domestic laws.