Face masks can be made mandatory in a densely populated city provided that there are multiple areas with a high risk of COVID-19 contamination, France's high court said on Sunday.
France's health minister had appealed a legal challenge to local decrees making face masks mandatory in Lyon and Strasbourg due to the active circulation of coronavirus.
France's high court, which advises the government, said that masks can be imposed "in large areas if the mandate is coherent and easy to apply for citizens."
But, they continued, the areas should be "limited -- and justified -- by the existence of multiple zones at high risk of contamination".
The court ruled that face masks could thus be made obligatory in densely populated cities such as Lyon and Strasbourg. But in less densely populated villages or cities, masks cannot be made mandatory.
The decision came after lower courts in both cities said that the mask mandates had to be limited to streets and hours of the day when the cities were most crowded.
Lyon's city's lower court said in a press statement issued last week that the expansion of the mask mandate to the entire city was too "general and absolute" and thus interfered with "the freedom to come and go and the rights of everyone in terms of their personal freedom."
A civil liberty group called "Les Essentialistes" brought the case against authorities arguing that the face mask decrees were disproportionate and inefficient.
But France's high court said that perimeters of a mask mandate should be "large enough" so that it is clear for citizens and so they are not removing their mask multiple times.
The ruling comes as the Rhône department, where Lyon is located, recorded roughly 400 new coronavirus cases per day last week. The incidence rate has also skyrocketed, climbing to a rate just behind Paris and Marseille, with 112 new cases per 100,000 people.
The area is one of 28 French departments that is a "red zone" with more than 50 new cases per 100,000 people.
France has been one of the most heavily impacted countries due to COVID-19 and recorded an all-time high in the number of daily reported cases on Friday, with a total of 8,975.
The government has said they would like to do everything possible to avoid a second lockdown, including issuing local restrictions if necessary.
Early on in the crisis, French officials, like other western officials, repeatedly insisted that masks were useless to protect against COVID-19 in the general population, a move that some say has led to incoherence in their post-lockdown strategy.
Since then, scientists have said that face masks help to protect others by preventing droplets from being transmitted by people who may not know they have COVID-19.
Face masks have been mandatory in closed indoor spaces in France since July 18 but only in August did cities begin to make them mandatory in outdoor public spaces as COVID-19 cases began to significantly rise across the country.