Officials promised the opposition leader, Mehdi Karroubi, 79, that the 12 guards watching over him around the clock would no longer be permanently stationed in his house, his son, Mohammad Taghi Karroubi, said. Mehdi Karroubi, who has been held under house arrest in Tehran since 2011, will remain so, but the government also promised to “endeavor” to realize his longstanding demand for a public trial, his son told the Saham news website.