The Supreme Court on Monday allowed the third version of the Trump administration’s travel ban to go into effect while legal challenges against it continue. The court’s orders mean that the administration can fully enforce its new restrictions on travel from eight nations, six of them predominantly Muslim. For now, most citizens of Iran, Libya, Syria, Yemen, Somalia, Chad and North Korea will be barred from entering the United States, along with some groups of people from Venezuela. The restrictions vary in their details, but in most cases, citizens of the countries will be unable to emigrate to the United States permanently and many will be barred from working, studying or vacationing here. Iran, for example, will still be able to send its citizens on student exchanges, though such visitors will be subject to enhanced screening. Somalis will no longer be allowed to emigrate to the United States, but may visit with extra screening.