The US Supreme Court has signaled support for the Trump administration's plan to ask each person in the country if they are an American citizen.

According to Bloomberg, key justices "seemed inclined to let the Trump administration add a question about citizenship to the 2020 census" during Tuesday oral arguments.

Hearing arguments in Washington, Chief Justice John Roberts and Justice Brett Kavanaugh directed almost all their questions to the lawyers challenging the decision to ask about citizenship. Kavanaugh said Congress gave the Commerce secretary "huge discretion" to decide what to ask on the census. -Bloomberg

Chief Justice: "quite common" for demographic questions to be asked in the census

Kavanaugh: "very common" in other countries for citizenship question to be asked — Lawrence Hurley (@lawrencehurley) April 23, 2019

At census args today, the justices sure looked like they had made up their minds and if so it’s 5-4 to uphold adding citizenship Q to the census form. #SCOTUS — Nina Totenberg (@NinaTotenberg) April 23, 2019

The Constitution requires that the government survey all "persons" living in the United States each decade. Until 1950, the census regularly asked about citizenship - however it was discontinued out of fears that it would harm participation.

Commerce Secretary Wilbur Ross, who oversees the census, has indicated that he wants to reinstate the question at the request of the Justice Department in order to improve enforcement of the federal voting rights law, reports ABC News.

Commerce Secretary Wilbur Ross

New York state and several civil rights groups sued Ross, calling his stated rationale a pretext for discrimination and a politically motivated attempt to generate an undercount in heavily Democratic areas. By the administration's own estimates, asking about citizenship is projected to drive down the census count by about 6.5 million people, mostly among immigrants and their families. -ABC News

"The citizenship question is a bald-faced attempt to racially rig the census, undercount communities of color and undermine fair representation which our democracy relies upon," said Common Cause president Karen Hobert Flynn.

The Trump administration, meanwhile, calls critics' claims unfounded, and says that it's highly "speculative" to assume that millions of people woud decline to participate in the census because of a citizenship question, or that immigration status would be used as a political weapon to retaliate against opponents.

"The Secretary concluded as a matter of policy that 'even if there is some impact on responses, the value of more complete and accurate [citizenship] data derived from surveying the entire population outweighs such concerns,'" wrote Solicitor General Noel Francisco in court documents.

Ross's plan has been challenged three times by federal judges this year, all of whom found that the Commerce Secretary acted illegally, in an "arbitrary and capricious" manner to circumvent the Administrative Procedures Act requiring that federal agencies carefully study ssuch measures before implementing new policies.

Francisco disagreed - writing in court filings "The Secretary's decision to reinstate the citizenship question is committed to agency discretion by law and thus judicially unreviewable," adding "Questions about citizenship or country of birth (or both) were asked of everyone on all but one decennial census from 1820 to 1950, and of a substantial portion of the population on every decennial census (on the so-called ‘long form' questionnaire) from 1960 through 2000."

The case is the first analysis of a Trump administration initiative since they upheld President Trump's travel ban last year.