In a judgment delivered on February 28, 2020, the Supreme Court of Canada held (by majority, 7–2) that Canadian common law does not contain an all-encompassing doctrine of non-justiciability based on foreign acts of state; and (by a narrower majority, 5–4) that alleged breaches of customary international law (CIL) arguably provide a novel cause of action in tort. The court held that claims against a Canadian mining corporation related to alleged violations at a mine in Eritrea could proceed to trial.

On December 20, 2019, the Supreme Court of the Netherlands published its judgment in The State of the Netherlands v. Urgenda. The judgment is largely a discussion of questions of Dutch law, but contains several conclusions that are relevant from an international law perspective. In particular, the Court held that on the basis of the European Convention on Human Rights (ECHR), the Netherlands has a positive obligation to take measures for the prevention of climate change and that it was required to reduce its greenhouse gas (GHG) emissions by at least 25 percent by the end of 2020, compared with 1990 levels.

On March 28, 2019, the First Instance Division of the East African Court of Justice (the EACJ or Court) issued a judgment in Media Council of Tanzania and Others v. Attorney General of the United Republic of Tanzania, Reference No. 2 of 2017. The Court held that several provisions of United Republic of Tanzania's Media Services Act 2016 (the Act) violated the freedom of expression at the heart of the fundamental and operational principles enshrined in Articles 6(d) and 7(2) of the Treaty Establishing the East African Community (the EAC Treaty).

The Supreme Court of the United States has decided four cases under the 1980 Hague Convention on the Civil Aspects of the International Child Abduction (hereinafter the Hague Convention), the most recent one coming this term in Monasky v. Taglieri. The Hague Convention, adopted in 101 countries, requires the judicial or administrative authority of a country that is party to the Convention to return a child who has been wrongfully removed or retained to the country of the child's habitual residence.The Convention also provides for a limited number of defenses to return. The obligation of return is a “provisional” remedy, in that the merits of any custody dispute will be determined by a court in the country of habitual residence. One of the most critical aspects of the Convention is this concept of “habitual residence,” which was the issue presented to the Court in Monasky.

In January 2020, the UN Human Rights Committee ruled that states cannot deport people who face “climate change-induced conditions that violate the right to life.” According to a UN press release, the complaint in this case was filed by Ioane Teitiota who was denied asylum in New Zealand and deported with his family to his native Kiribati. Following his deportation, he filed a complaint with the Human Rights Committee, alleging that his deportation violated his right to life and that the rise of the sea level and other climate change impacts rendered Kiribati uninhabitable. Though the Committee determined that, on the facts, Mr. Teitiota's right to life was not violated, the Committee specifically indicated that “"this ruling sets forth new standards that could facilitate the success of future climate change-related asylum claims.” In particular, the Committee determined that asylum seekers need not demonstrate that they would face imminent harm if returned to their home states because the negative effects of climate change can occur suddenly and more slowly, over the longer-term.