In recent months, lawyers across the US have brought dozens of lawsuits on behalf of ordinary citizens and non-profit groups arguing that a section of the 14th Amendment to the US Constitution bars the former president from holding a second term, because of his role in the January 2021 storming of the US Capitol.

Others have petitioned the top officials in 50 states with responsibility for overseeing elections and enforcing rules.

In the most high-profile victory to date, the top court in Colorado in December judged Mr Trump was ineligible to serve and said his name should not appear on the state’s primary election ballots.

“[My clients] believe in the law. The law is clear and when the law is clear they feel it should be followed,” Mario Nicolais, who represents six voters in the Colorado case, tellsi.

Mr Nicolais, of Denver-based KBN Law, adds: “In this case, the law does not allow for President Trump to be on the ballot again in Colorado.”

As with many lawsuits across the country, the case brought by Mr Nicolais, with the backing of the group Citizens for Responsibility and Ethics in Washington, focuses on Section 3 of the 14thAmendment, adopted in 1867 after the US Civil War.

It prohibits from holding elected office or serving as an “officer of the United States”, anyone who swore an oath to “support” the constitution and then “engaged in insurrection or rebellion”.

Its adoption came after former confederates, including the Confederacy’s vice president, were sent by voters in the South to Washington DC to serve in Congress. The government felt so-called “unrepentant” confederates should not benefit in this way after starting a war that killed at least 600,000 Americans.

Last November a Colorado judge ruled that while Mr Trump had engaged in insurrection during the 6 January attack, he should remain on the ballot as it was unclear whether the Civil War-era provision applied to the office of the presidency.

The plaintiffs, among them 91-year-old Norma Anderson, a state Republican who served in the Colorado House and Senate, appealed the decision. In December, the Colorado Supreme Court ruled 4-3 in their favour, ordering that Mr Trump was not eligible for a second term, but staying its decision until the US Supreme Court had a chance to weigh in.

“We do not reach these conclusions lightly,” the court said. “We are mindful of the magnitude and weight of the questions now before us. We are likewise mindful of our solemn duty to apply the law, without fear or favour, and without being swayed by public reaction.”

Praveen Fernandes, vice president at the Constitutional Accountability Centre, is among those watching the US Supreme Court’s impending decision with interest.

His group was among several that sent “amicus briefs” to courts that considered Mr Trump’s eligibility, including the top court in Colorado, which agreed with its argument the president was “an officer of the United States”.

“It was the issue on which the case turned,” he says.

He says one thing the court is not supposed to consider is whether or not a decision is popular. He also says Congress has the option to change the 14th Amendment if it wishes.

It is the court’s job, however, to consider the law. “If text and history are their guideposts, the justices will uphold the Colorado State Supreme Court decision,” he says.

He says several justices have declared themselves “textualists” who prioritise the language of a law.

He adds: “If those truly are their guideposts for interpreting the Constitution, the text and history here are relatively clear and Donald Trump – through his actions relating to January 6 – is disqualified from office.”

Another case to have made headlines is that in Maine, which last month also stripped Mr Trump from the primary ballot. The decision was taken by Maine Secretary of State Shenna Bellows, a Democrat, who said she made the call after hearing evidence.

“I am mindful no Secretary of State has ever deprived a presidential candidate of ballot access based on Section Three of the 14th Amendment,” she said. “I am also mindful, however, that no presidential candidate has ever before engaged in insurrection.”

Mr Trump has appealed the judgements in Maine and Colorado, denouncing them as “partisan election interference”.

Elsewhere, Mr Trump has had more success. In about a dozen states, including the battleground of Michigan, along with Minnesota, Oregon, and Arizona, courts have ruled he can seek a second term, though those decisions are also being challenged.

In a dozen others, including California and Florida, the issue remains unresolved.

John Bonifaz, president of the non-profit Free Speech For People, says his group wrote to each top state election official urging them to disqualify Mr Trump. Only Ms Bellows in Maine took action, though her move has been paused by a judge there.

He says chief election officers are responsible for enforcing such laws.

“They need to look at constitutional qualifications,” he tells i.

Mr Bonifaz noted that along with the insurrection clause, these included not putting on the ballot anyone under the the age of 35, or anyone who is not a “natural born citizen”, namely someone who was a citizen at birth and did not need to go through a naturalisation process.

He said the law does not require someone to have been found guilty of insurrection by a criminal court.

Asked whether people – particularly Trump supporters – will lose faith in the legal and political system if he is barred by a Civil War-era provision not tested for more than 150 years, he says: “The danger is ignoring a critical provision of the Constitution designed to protect our country – that is the danger.”

Earlier this month, the US Supreme Court said it will examine the Colorado Supreme Court ruling, mindful the voting process for the 2024 election is already underway following the caucuses in Iowa and primary in New Hampshire, both of which Mr Trump won handily.

It has, however, declined a request from Department of Justice appointed special counsel Jack Smith to swiftly rule on Mr Trump’s claim that he is immune from prosecution in a case charging him with plotting to overturn the 2020 presidential election.

Many commentators believe the court was loath to take up such a case after the backlash to its 2000 ruling that effectively awarded the presidency to George W Bush rather than Al Gore. At the same time, the court – which has a six-three conservative majority – would not want to enter election year with Mr Trump’s eligibility being decided on a state-by-state basis.

Mr Trump’s effort to gain access to the ballot is only one of the legal challenges he confronts as he seeks a second term as president.

He faces 91 criminal charges ranging from an alleged illegal hush money payment to an adult film actor in New York, to accusations in Georgia he pressured election officials to help rig the election.

Mr Smith, the special prosecutor, has charged him with conspiracy over his alleged spreading of false claims the 2020 election was rigged and his efforts to prevent the certification of Joe Biden’s victory. He also faces up to 40 counts over his alleged retention of government documents, including classified materials.

Mr Trump has denied all the allegations and made his defence a central part of his election campaign, raising money and seeing his ratings soar as more indictments land. On some days, he has attended a court hearing only to later headline a campaign rally that evening.

Some critics claim Mr Trump is only seeking a second term to secure the right to pardon himself and others if he becomes president again. At the same time, there is nothing in the Constitution that bars someone from serving as president if convicted, even in theory, if they were in jail.

Last May Mr Trump, 77, was found liable in a civil trial for sexually abusing columnist E Jean Carroll in 1996 and ordered to pay $5m. Ms Carroll has also sued Mr Trump for libel over claims he made that he did not know her and did not attack her.

Last week, a jury ordered Mr Trump to pay Ms Carroll an additional $83.3m in damages.

Also last year, a judge in New York found Mr Trump and his adult sons liable for fraud in another civil trial, in which he was accused of vastly inflating the value of his various holdings and properties, including Mar-a-Lago, in order to get better interest rates from banks.

New York Attorney General Letitia James is seeking $250m in damages and a ban on the Trumps serving as officers of a business in the state. Mr Trump also pleaded not guilty in that case and has appealed it.