The Trump administration asked the Supreme Court to issue an unusually quick ruling on the Pentagon's policy of restricting military service by transgender people.

It's the fourth time in recent months the administration has sought to bypass lower courts that have blocked some of its more controversial proposals and push the high court, with a conservative majority, to weigh in quickly on a divisive issue.

Earlier this month, the administration asked the high court to fast-track cases on the President's decision to end the Deferred Action for Childhood Arrivals programme, which shields young immigrants from deportation. Administration officials also recently asked the high court to intervene to stop a trial in a climate change lawsuit and in a lawsuit over the administration's decision to add a question on citizenship to the 2020 census.

The 9th US Circuit Court of Appeals, a frequent target of criticism by President Donald Trump, is involved in three of the cases. Trump's recent salvo against the 'Obama judge' who ruled against his asylum policy — not one of the issues currently before the Supreme Court — prompted Chief Justice John Roberts to fire back at the president for the first time for feeding perceptions of a biased judiciary.

Joshua Matz, publisher of the liberal Take Care blog, said the timing of the administration's effort to get the Supreme Court involved in the issues at an early stage could hardly be worse for Roberts and other justices who have sought to dispel perceptions that the court is merely a political institution, especially since the confirmation of Justice Brett Kavanaugh. At an especially sensitive moment for the Supreme Court, the Trump administration is 'forcing it into a minefield that many justices would almost surely prefer to avoid,' Matz said.

The Supreme Court almost always waits to get involved in a case until both a trial and appeals court have ruled in it. Often, the justices wait until courts in different areas of the country have weighed in and come to different conclusions about the same legal question.

So it's rare for the justices to intervene early as the Trump administration has been pressing them to do. One famous past example is when the Nixon administration went to court to try to prohibit the publication of the Pentagon Papers, the secret history of US involvement in the Vietnam War.

In the immigration case, the administration told the high court that it should step in and decide the fate of DACA ahead of an appeals court's ruling because the policy otherwise could be in place until the middle of 2020 before the justices might otherwise rule. The appeals court has since ruled, but the administration's request that the court hear the case stands.

In the military case, the administration argued that the Supreme Court should step in before an appeals court rules because the case 'involves an issue of imperative public importance: the authority of the US military to determine who may serve in the Nation's armed forces'.

In a statement, Peter Renn, an attorney for Lambda Legal, which brought one of the challenges to the transgender military policy, called the Trump administration's action Friday a 'highly unusual step' that is 'wildly premature and inappropriate.'

The Pentagon initially lifted its ban on transgender troops serving openly in the military in 2016, under President Barack Obama's administration. But the Trump administration revisited that policy, with Trump ultimately issuing an order banning most transgender troops from serving in the military except under limited circumstances. Several lawsuits were filed over the administration's policy change, with lower courts all ruling against the Trump administration.

Still ongoing in lower courts are the census and climate change cases. The Supreme Court for now has refused to block the climate change trial. In the census question case, the court has agreed to decide what kind of evidence a trial judge can consider and indefinitely put off questioning of Commerce Secretary Wilbur Ross. But it rejected an administration request to delay the trial and allowed other depositions to take place.

The court will hear arguments in the census question case in February. It's unclear when it will act on the administration's other requests.