Sunday shopping or Sunday trading refers to the ability of retailers to operate stores on Sunday, a day that Christian tradition typically recognises as a day of rest. Rules governing shopping hours, such as Sunday shopping, vary around the world but some countries and subnational jurisdictions continue to ban or restrict Sunday shopping.

Erwin Fahlbusch and Geoffrey William Bromiley write that throughout their existence, organizations advocating first-day Sabbatarianism, such as the Lord's Day Alliance in North America and the Lord's Day Observance Society in the British Isles, were supported by labor unions in lobbying "to prevent secular and commercial interests from hampering freedom of worship and from exploiting workers."[9][10] For example, the United States Congress was supported by the Lord's Day Alliance in securing "a day of rest for city postal clerks whose hours of labor, unlike those of city mail carriers, were largely unregulated."[2] Before the liberalisation of shop opening hours in a country like Austria, for example, one could observe an increase in cross-border shopping towards countries with more liberal shopping hours.[1]

Studies of liberalisations in North America and Europe suggest that Sunday shopping interdictions depress employment growth, harm prospective workers with non-traditional schedules, and may not protect consumers from price increases. Although research has confirmed the suspicion that larger outlets benefit to a greater extent from the liberalisation of shop-closing regulations than their smaller counterparts, such regulations serve only to protect the inefficiency of the latter, thereby harming consumers.[3]

It has not been proven that Sunday shopping hurts retailers by leading all of them to open longer hours. Consumer preferences can point in the direction of an extension of shop opening hours in a given area without this need arising in another area. In Spain, for instance, where relatively few restrictions survive, retail stores are open an average of 46 hours per week. In Sweden, 15 years after liberalisation, supply as regards shop opening hours has not yet standardised itself. On the contrary, if 80% of the department stores and supermarkets are open on Sunday, only half of corner shops and 48% of furniture stores are open on this day.[1]

Final extension of opening hours, for each individual firm, will depend on:[1]

An economic model of free competition in prices and opening hours with free entry has shown that restrictions on opening hours aggravate a market failure: entry is excessive and opening hours are underprovided. The model predicts the impact of a liberalization of opening hours: in the short run prices will remain constant, but increase in the long run. Concentration in the retail sector will rise and opening hours will increase in two steps, immediately after deregulation and further over time. Finally, employment in the retail sector increases.[4]

Campaigns for deregulation of Sunday shopping have been put forward mainly by liberal parties. But as long ago as 1899,[

Campaigns for deregulation of Sunday shopping have been put forward mainly by liberal parties. But as long ago as 1899,[5] even US Christian churchgoers were calling for a reform of the laws in the US, because the result was not more people going to Church but "enforced idleness": George Orwell uses the term in Down and out in Paris and London to remark that the worst problem of the underclass is being made to wait.[6][7] In "The Spike", an essay about workhouse conditions, Orwell remarks that one could not leave on a Sunday but was bound over until the Monday.[citation needed]

Prison reformists often argue that enforced idleness in prison helps neither those inside nor outside.

Arguments in favour of regulation of shop opening hours usually emanate from trade unions and industry federations, as well as socialist and Christian democratic parties. They include:[1]