The plan to lock down large swaths of the north was the first major attempt by a democracy during the coronavirus crisis to radically halt the routines of daily life — an effort that will have significant impacts on civil liberties. But in the hours before and after the measure became law, people continued to stream out of the northern hubs of Milan and Venice on trains and planes for southern Italy or elsewhere in Europe.

Sunday, then, provided the first glimpse of a coronavirus lockdown, European-style — a test of how the open-borders spirit of this continent might change as countries grapple with the scale and risks of the disease.

As the day went on, it became clear that Italy was not trying to impose anything close to the absolute movement restrictions that have been enforced by China. Some analysts pointed out that even limited movement outside Italy’s north risked further spreading the virus, and for the first time a European Union leader — Czech Prime Minister Andrej Babis — suggested Italy’s government needed to do more to interrupt the flow of its citizens across the bloc’s borders.