国际法的两大支柱：习惯法与条约
国际法（International Law: 由国家制定并供国家遵守的复杂规则体系）是维系现代世界运转的基石，其规制范围涵盖了从食品安全到战争的方方面面。尽管各国利益不同且时有冲突，但仍通过特定的方式达成了规则共识。国际法主要有两个核心来源：习惯法（Customary Law: 虽未形成书面文字，但被各国广泛且一致遵守并视作法律的实践行为）和条约（Treaties: 拥有正式名称与标题的官方书面协议）。
以习惯法为例，海难救援即是一项典型的习惯法实践：任何船只在海上遇到处于危难之中的人员时，均有义务提供援助。另一个典型例子是外交豁免权（Diplomatic Immunity: 外交官在执行公务期间免受驻在国刑事起诉的权利）。这两项规则在正式写入国际条约之前，已经在国际社会中作为习惯法被默默遵守了许多年。
Original English Source
International law is a complex set of rules that are made by countries for countries to follow, and these rules make the world tick. They regulate everything from the food we eat... to war. So, how do countries, which often have different and sometimes competing interests, come to agree on what these rules are? Let's unravel how international law is made. There are several sources of international law. We're going to focus on the two major ones - customary law and treaties. Let's start with customary law. So, there must be a practice that many countries consistently do, and that practice is accepted as law, even if it isn't written down. It's kind of like a social norm, like take your shoes off when you enter someone's home. An example of customary international law is the idea of rescuing people at sea. Any ship that comes across people in distress is obligated to provide help. Or take another example: diplomatic immunity - the idea that diplomats can't be prosecuted with a crime while they're on the job. Both of these were accepted as customary law for years before they were written into a treaty.条约制定的前置环节：议题识别与外交谈判
相比于习惯法，条约是更具约束力的第二大国际法来源。条约可以通过双边谈判（Bilateral Negotiation: 两国之间的谈判）或多边谈判（Multilateral Negotiation: 多个国家之间的谈判）来完成，有时多边协定的谈判会借助联合国（United Nations）等国际组织来进行。联合国的一项重要工作就是保管条约库，以便各国明确知晓谁签署了哪些条约以及具体条款。
制定条约的第一步是识别议题。这些议题可以是需要通过条约解决的共同挑战，例如臭氧层消耗、航行自由、南极洲保护，也可以是为了消除贸易壁垒等潜在争端。一旦各方就存在问题达成共识，便会启动谈判。在谈判阶段，利益相关国将决定条约的具体文本内容。在加拿大，内阁负责授权启动这一进程，并指定谈判代表并提供谈判指南。虽然名义上由加拿大全球事务部（Global Affairs Canada）监管、外交部长负责代表国家谈判，但在实际操作中，其他相关部门也会根据条约主题直接参与具体谈判。谈判达成一致后，国家代表会签署条约以示对文本的支持，一旦签署，条约文本便不能再做任何修改。
Original English Source
The second major source of international law are treaties, agreements, or conventions with official names and titles. These can be negotiated bilaterally, meaning between two countries, or multilaterally, meaning between several countries. Sometimes, multilateral agreements are negotiated through organizations such as the United Nations. In fact, one of many jobs the UN does is to keep a library or collection of treaties, and that's so everyone knows which countries signed which treaties and what those treaties say. Okay, so, how are treaties made? That is a long, complicated, multi-step process. And the first step is finding an issue that needs to be sorted out through a treaty. It could be a common problem to solve, let's say ozone depletion, or freedom of navigation, or protecting Antarctica, you name it. Or it could be settling some kind of a potential dispute, if countries have trade barriers, for example, and eventually, they want to arrive at a place where those trade barriers are removed. So, the first thing is to identify the issue. Then, comes negotiation. This is the part where interested countries decide what goes into the treaties, literally what the text of the treaty will be. Once there is agreement that there is an issue, negotiations will be launched. Issues might arise as to who should participate in these negotiations. Is this something that requires universal involvement or is it only a regional issue? Here in Canada, cabinet authorizes the start of this process and the Minister of Foreign Affairs is responsible for negotiating international treaties on our behalf. Well, that's the case on paper at least. In practice, other departments also carry out negotiations, depending on what the treaty is about, with the supervision of Global Affairs Canada. Cabinet is responsible for appointing negotiators and giving them guidelines for negotiations. Once a treaty is negotiated, countries will sign it, showing they support the text of the agreement. The Prime Minister and the Minister of Foreign Affairs have the power to sign international treaties for Canada. No more changes should be made to the text of an agreement after it's signed.从国内法转化到条约生效的法理闭环
签署条约并不意味着其自动在国家内部产生法律效力，接下来必须经过实施（Implementation: 将国际条约内容转化为国内法律的过程）环节。这意味着条约规则必须体现在国内法中，这通常需要修改现有的国内法律或制定全新的法律。由于部分事务可能属于联邦管辖，部分属于省管辖，国内立法转化过程往往十分复杂。如果条约内容与现有国内法已完全一致，则无需额外行动。
在完成国内法转化后，条约将进入批准（Ratification: 国家权力机关正式确认并接受条约约束力的法律行为）阶段。以加拿大为例，当内阁批准条约时，条约在国际法层面上便对加拿大产生法律绑定效力。条约生命周期的最后一步是正式生效（Coming into Force）。这通常发生在所有缔约方均完成批准程序之后的约定日期，自该日起，各国必须严格遵守条约的条款。
Original English Source
Now, what comes next is a step called implementation. What that means is that treaties must be reflected in Canadian law. You will find implementing legislation sometimes scattered over different types of domestic legislation. Sometimes, some of the subject matter might be provincial jurisdiction, some of it might be federal jurisdiction, so it can be quite complicated. In some cases, that involves either changing existing domestic law to make it consistent with a treaty or creating a brand new law. But sometimes, a treaty is already reflected in domestic Canadian law, in which case, no further action is needed. That would take us to the next step: ratification. Ratification is when cabinet approves the treaty, and that makes it legally binding on a country, meaning a country is obligated to follow it. When a treaty is ratified by Canada, when Canada opts in and binds itself, then that treaty is binding on Canada under international law. The last step is a treaty coming into force on an agreed-upon day. That happens after all parties have ratified it. Countries have to abide by the terms of the agreement from that day forward.条约演进的实证：从NAFTA到CUSMA的重塑历程
为了清晰理解上述流程，我们可以回顾**《加拿大-美国-墨西哥协定》**（CUSMA: 加美墨自由贸易协定，旧版为 NAFTA）的诞生过程。CUSMA 的前身是 1994 年 1 月 1 日生效的《北美自由贸易协定》（NAFTA）。2016 年，时任美国总统候选人唐纳德·特朗普（Donald Trump）批评 NAFTA 是“有史以来最糟糕的贸易协定”，并极力主张重新谈判。
在经历超过 20 年的运行后，美、加、墨三国于 2017 年 8 月 16 日正式启动了 NAFTA 替代协定的谈判。加拿大谈判团队由时任外交部长方慧兰（Chrystia Freeland）领衔。历经数月艰苦博弈，三国代表于 2018 年 11 月 30 日签署了新贸易协定。随后，加拿大国内启动了实施立法程序，相关法案于 2020 年 3 月 13 日在议会通过。几周后，加拿大官方正式批准了该协定。最终，CUSMA 于 2020 年 7 月 1 日正式生效，有效期设定至 2036 年。该条约还允许三国在到期前重新谈判，而一旦启动重新谈判，上述条约制定的全套流程又将重新循环。
Original English Source
Okay, so, we outlined the steps. Now, let's take a look at an example. Like CUSMA - the Canada-United States-Mexico Agreement. It's the successor to NAFTA, the North American Free Trade Agreement. NAFTA came into force on January 1st, 1994. In 2016, then US presidential candidate Donald Trump called the agreement... The worst trade deal maybe ever signed anywhere. He argued that the treaty, which, at that point, was over 20 years old, needed to be renegotiated, and negotiations for NAFTA's replacement began on August 16, 2017. Canada's team was led by then Minister of Foreign Affairs, Chrystia Freeland. And after months of negotiations, all three countries signed the agreement on November 30, 2018. Let's go. Let's go. Let's go. The new treaty, CUSMA, needed implementation legislation here at home. A bill entitled "An Act to Implement the Agreement between Canada, the United States of America and the United Mexican States" be now read a first time and be printed. That bill passed on March 13, 2020. Canada officially ratified CUSMA a few weeks later, and the treaty finally came into force on July 1st, 2020, with an expiration date set to 2036. The treaty also allows the countries to renegotiate the deal before it expires, which would start this process all over again.📌 文中提及的人物和组织
人物: Donald Trump, Chrystia Freeland
公司/组织: United Nations