Legality of agreement between countries
<p>How can a contract be established and enforced if the parties are countries?</p>

<p>There is nothing in perpetuity, how can contract negotiated by fathers bear upon children. Can not children defy contract unilaterally?</p>

<p>I am particularly interested in the <a href="https://en.wikipedia.org/wiki/Indus_Waters_Treaty" rel="nofollow noreferrer">Indus Water treaty</a>.</p>

<p>If India simply stops observing that treaty, what can Pakistan do?</p>

<p>A treaty is not a contract. Even so, if one party unilaterally breaches a contract, then they are indeed in breach and can be sued for damages. As with a contract, there are clauses about modifying or terminating the agreement by mutual agreement. The treaty does not bind individuals, it binds nations, so the actions of the father are <em>not</em> inherited by the actions of the son, even if some people living in India and Pakistan were not born when the treaty was negotiated. (Observe that with a contract between individuals, each party must agree, and clearly the individual citizens of India and Pakistan did not all agree to this). India is India, Pakistan is Pakistan. However, it is a technically open question whether <a href="http://www.financialexpress.com/india-news/indus-water-treaty-with-pakistan-pil-filed-in-supreme-court-challenging-its-constitutional-validity/391485/" rel="nofollow noreferrer">India legally entered into the treaty</a>.</p>

<p>One of the powers that sovereign nations have is to make treaties with other sovereign nations, these can be bi-lateral (as in the example you cite) or multi-lateral (like the Maastricht Treaty that binds the EU together). Once a treaty is agreed and signed it needs to be <a href="https://en.m.wikipedia.org/wiki/Ratification" rel="nofollow noreferrer">ratified</a> by each country which makes it part of the <em>domestic</em> law in that country: for your example, if India breaches the treaty it can be taken to court under the laws and in the courts of India <em>or</em> Pakistan.</p>

<p>Treaties may have a sunset date and almost always have dispute resolution clauses, often requiring international mediation or arbitration. They may also have termination clauses like article 50 of the EU treaty (the "Brexit" clause).</p>

<p>One of the legal fictions of the doctrine of sovereignty is that nations are indissoluble and eternal. In practice, nations come and go (albeit rarely) and while this has legal consequences the process is actually extra-legal, always political and often martial. The worlds newest nation is, I believe, South Sudan, and one that has recently vanished is Yugoslavia.</p>

<p>Laws are not contracts: contracts require consent of the parties, among other things., laws don't, they are imposed irrespective of consent.</p>

international treaty sovereignty