---
title: "Articles 20–27: Vienna Convention on Treaties"
description: "Articles 20–27 of the Vienna Convention on the Law of Treaties outline treaty reservations, essential for diplomats and policy researchers in international law."
url: "https://modeldiplomat.com/learn/glossary/articles-2027"
---

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Model Diplomat Research Team · Last reviewed June 22, 2026

TL;DR

- Articles 20–27 of the Vienna Convention on the Law of Treaties (1969) govern reservations to treaties, including their acceptance, objection, legal effects, and withdrawal.
- What is the compatibility test for reservations under the VCLT?
- What does Article 27 of the VCLT provide?
- How long does a State have to object to a reservation under Article 20?
- What is the legal effect of a reservation under Article 21?

[Civil Service & Diplomatic Exams](https://modeldiplomat.com/learn/civil-services/glossary)Updated June 22, 2026

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## Research Articles 20–27 like a delegate

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## Timeline

1. 23 May 1969

   Articles 20–27 form the core operative provisions of the Vienna Convention on the Law of Treaties (VCLT), concluded at Vienna on and in force since 27 Janua…

2. 27 January 1980

   Articles 20–27 form the core operative provisions of the Vienna Convention on the Law of Treaties (VCLT), concluded at Vienna on 23 May 1969 and in force sin…

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[Start research on Articles 20–27](https://modeldiplomat.com/search?q=Explain%20Articles%2020%E2%80%9327%20%E2%80%94%20key%20dates%2C%20actors%2C%20positions%2C%20and%20sources)

Example

When the United States ratified the ICCPR in 1992, it lodged reservations to Article 6 on the juvenile death penalty; eleven European States objected under VCLT Article 20 while accepting the treaty's entry into force between them.

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