Rights activists are trying to force President Abdel Fattah al-Sissi to throw out a law used by his government to imprison thousands of Egyptians and sentence hundreds to death by arguing that it was overturned as far back as 1928.
Over the past three years, judges have cited Law 10 of 1914, or the Assembly Law, in jailing opposition activists and ordinary people for protesting against Sissi and his government and in issuing mass death sentences, mainly to Islamists.
Security forces also cite it to justify the use of force against demonstrators that has led to thousands of deaths, a crackdown they say is in response to fatal attacks on police and soldiers and is needed to preserve stability in the most populous Arab state.
Little was known about the history of the Assembly Law until human rights groups decided to delve into the archives. The Cairo Institute for Human Rights Studies (CIHRS) non-government organization published a 95-page report on Tuesday.
The law, which criminalizes the gathering of five or more people and institutes collective punishment, was issued at the behest of British occupation authorities to stop Egyptians protesting against their rule in the lead up to World War I.
What the researchers uncovered was that in 1928, the then-parliament passed a bill to repeal it.
The bill should have passed into the statute book because the monarch at the time, King Fuad I, neither signed nor vetoed it within 30 days. However the king, who objected to the repeal but knew any veto would be overturned, prevented it being published in the official gazette, leaving its legal status, and that of the original Assembly Law, unclear.
Despite this, successive post-colonial and republican governments continued to apply the Assembly Law at various stages. President Gamal Abdel Nasser, who overthrew the monarchy, even made it stricter in 1968 following student protests.
The researchers argue, however, that the fact that the 1928 repeal bill went unpublished did not detract from its legal status and that therefore the continued use of the Assembly Law was, and is, illegal.
Their findings prompted a group of 21 people, including two activists in jail because of the law, as well as lawyers and opposition party leaders, to launch a legal case on Tuesday. The case sets out the argument that the Assembly Law was repealed in 1928 and urges Sissi and the government to throw it out.
"It's time President Sissi takes the initiative to immediately renounce this historic and legal indignity by abolishing the British colonial administration law, originally designed to suppress Egyptian resistance to occupation," said Bahey eldin Hassan, director of CIHRS.
"Every citizen deprived of their freedom under this unjust, obsolete law must be immediately released, with apologies and reparations for their families."
The government and Sissi's office did not respond to requests for comment. The justice ministry declined to comment. One official, speaking on condition of anonymity, said they were unlikely to comment because the matter was with the courts.
The activists say they know it is unlikely the law will actually be repealed, and that even if it were repealed on a technicality, there is nothing stopping parliament, where most MPs are Sissi loyalists, from passing similar legislation.
Human rights groups estimate about 40,000 people have been detained for political reasons since 2013, when then-general Sissi ousted Egypt's first freely elected president, the Islamist Muslim Brotherhood's Mohammed Morsi, after mass protests.
The Assembly Law, along with a protest law issued in 2013, has effectively outlawed demonstrations and a judicial and security sweep that began with Islamists has expanded to include secular activists and journalists.
The law stipulates six-month prison sentences for any gathering of five or more people as long as police deem it a threat to public peace, even if no crime is committed.
If a crime, such as murder, is committed during the gathering, all those at the gathering and even those who call for it, even if they do not attend, are liable.
Correspondence in the British National Archives unearthed by CIHRS and seen by Reuters between the British High Commissioner in Egypt and the British Foreign Secretary shows the king, who faced protests, asked the British to stop parliament passing the bill repealing the Assembly Law but that they refrained.
Their thinking was that the law had served its purpose now the war was over and could no longer be justified to the British public, the correspondence shows.
CIHRS said its report was published two years later than intended due to a stepping up of pressure on Egyptian civil society workers, including travel bans and asset freezes.
It has prompted debate in parliament and the House of Representatives Committee on Legislative and Constitutional Affairs Chairman has called on the government to issue a statement clarifying the law's status.
To date, there has been no response from the government.