This question can be argued both ways.
On the one hand, it can be said that this sort of action on the part of the Supreme Court is unacceptable. The Constitution is an American document, not a document that has anything to do with any foreign country. Foreign courts and foreign judges have no duty to uphold the American Constitution. They are not trained in interpreting it and they are not a part of our legal tradition. Therefore, they should have no say in how our Supreme Court interprets our Constitution.
On the other hand, we can argue that foreign courts can provide information about current standards of justice. In this view, the Supreme Court is not being controlled by the foreign courts, it is just looking to them for information about how other people in the world think. This can be important, for example, in interpreting the 8th Amendment. That amendment forbids “cruel and unusual punishment,” but it does not tell us which punishments are “cruel and unusual.” Therefore, the Court is left to decide for itself what constitutes a cruel and unusual punishment in the modern world. In such a case, the Court might look to other countries. It is not looking to be told how to rule, instead, it is looking for others’ opinions to provide it with a variety of views on the subject.
I would argue that the Supreme Court should take into account the views of people in other countries, but it should never let itself be controlled by those views. It should only be taking advice (which it can reject), not orders.