If the judge does make this request, and the ECJ follows through with a ruling in their favour, it could ensure that UK nationals currently living in Europe will retain important rights such as freedom of movement.
The BBC reports that, under European law, the ECJ could potentially rule that all member states must guarantee the rights of Brits in the respective states in which they reside.
British barrister Jolyon Maugham, who is funding the legal action, told the BBC: “If the case is successful, all of us will continue to benefit from EU citizenship rights after Brexit.”
If the expats are successful, it could create a “politically awkward” situation, the British broadcaster reports.
“Those rights would no longer be a matter of political gift – EU law would continue to guarantee EU citizenship rights to those who are UK citizens at the date of Brexit.
“It would, potentially, weaken their position at the negotiating table,” Maugham said.
Earlier this month, a report by the Migration Policy Institute found that many British expats face “legal limbo” in applying for citizenship in the wake of the leave vote.