From a reader:

Jonah,
Our legal system does indeed harken back to the days of British common law for many issues, so your reader was correct that some countries share a common-law heritage that may make their common law decisions persuasive to our Supreme Court. However, decisions based on common law have at their root of authority simply the previous decisions of courts expounding on what the common law is. For constitutional law, though, we are dealing with an entirely different type of law, and the court derives its authority in the arena of constitutional law from, well, the Constitution. And since our Constitution is very different from Zimbabwe’s, I see no reason to give any precedential value to the Zimbabwean high court’s interpretation of its constitution. There’s nothing inconsistent about looking to foreign courts for precedents on issues of common heritage for common law decisions (Britain, before the U.S. developed its own courts, being the most obvious example) while refusing to look at foreign courts for guidance on interpreting a document uniquely American.
Sincerely,
A Concerned Harvard Law Alumni