Hillary Clinton may be able to challenge the election result in the Supreme Court and become the next President of the United States, a law professor has said.

Ms Clinton currently has 2.6 million more votes than Donald Trump in the popular count, but lost the election in November because of the idiosyncratic workings of the United States' Electoral College system — a result which academic Lawrence Lessig has said could be ruled unconstitutional.

The process by which the United States elects a president is complicated — rather than US citizens voting for their head of state directly, representatives in the Electoral College choose the winner on behalf of their state.

Almost all states operate a "winner-takes-all" system, which ignores voter margins. So for instance, Ms Clinton got 44 per cent of the vote in Georgia, but because Mr Trump got a larger percentage, none of the state's six representatives in the Electoral College are set to vote for her.

In an article published by Medium, Mr Lessig said he and a number of other legal experts believed this could be illegal because it defies the constitutionally enshrined principles of "equal protections" and "one man, one vote". It means not all votes are treated in the same way and some people do not get a say at all.

Mr Lessig, who is based at Harvard University, referred to a ruling the US Supreme Court made in 2000, when Republican lawyers litigated to stop a re-count of votes by the Democrats after a painfully close contest between George W Bush and Al Gore.

Although filed by Republicans to protect Mr Bush from being ousted in a re-count, Mr Lessig said a key decision about the importance of "equal protections" made by judges in that case could set a precedent in Ms Clinton's favour, if her party decided to mine the case for information.

But so far, the Democrats have been "timid" about doing this, he said.

"It is striking to see how committed they are to allowing this train wreck to occur," he said. "And more surprisingly, how little careful attention has been given (at the top at least) to just how vulnerable—given Bush v. Gore—the current (system for counting votes in the) electoral college is".

Electoral College voting: How the United States decides its president

All states except Maine and Nebraska currently allocate electors based on the winner-takes-all rule, but according to Mr Lessig that system for allocating electoral votes is not mandated by the Constitution, it is employed at the discretion of state.

In draft legal documents, Jerry Sims, an Atlanta lawyer, explores the argument in more depth, explaining that vast changes have occurred in state populations since the Electoral College system was adopted, exacerbating the problem by making the number of representatives allotted to each state disproportionate.

Over time, populations have concentrated in larger states, he said, meaning people from these states are increasingly under-represented in the Electoral College, making it an increasingly flawed system.

Over time it has become, and will continue to become, more and more common for a president to be elected despite having lost the popular vote, he suggested.

"A candidate who lost the popular vote has been elected President five times in US history," Mr Sims said.

"It has also occurred twice in the last 16 years. The 2000 election was the first time in US history that the candidate losing the popular vote won a majority of the Electoral College outright. Now that has happened again in 2016."

Echoing Mr Lessig, he added: "The major contributing factors to this outcome are the winner-takes-all system of allocating electors coupled with the growing concentration of the US population in a handful of States. These factors create a substantial risk that a candidate that loses the popular vote would win the Electoral College outright".

Under the current system, Mr Sims said, some voters are essentially being denied any say, and this is not legal.

"In Georgia, for example, we have 16 Electors and approximately 44 per cent of all voters cast ballots for Clinton," he said. "Yet the Clinton Voters receive no representation within the State’s Electors. They are left with no voice whatsoever in the election of the President by the Electoral College, their votes are for all practical purposes thrown away,"

He added: "If Georgia were electing a single candidate then a winner-take-all result would be proper, but in an election of 16 Electors, the Clinton votes are not being given equal dignity with the Trump votes."

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Mr Sims said that by far a fairer and more constitutional system would be for electors to be allocated proportionately, "in order to give every vote equal dignity and weight".

"Under this methodology [proportionately] every vote counts," he said. "Proportional allocation of Electors respects the one man one vote principle."

Mr Sims said the current system represents an "unconstitutional violation of the equal protection clause of the 14th Amendment and its bedrock principle of one man one vote," and therefore the election result could in theory be overturned by a court.

Mr Lessig criticised the failure of those "at the top" to consider launching a legal challenge.

"What about the unfairness being felt by the millions of voters whose votes were effectively diluted, or essentially disenfranchised?" he said, suggesting the Attorney Generals of large states such as New York or California could easily walk into the Supreme Court and ask them to hear a case.