Use of a grand jury to investigate links between Trumps presidential team and Russia could be very serious. Heres what you need to know about grand juries

It has emerged that US special attorney Robert Mueller is use a grand jury in Washington as part of an investigation into potential coordination or collusion between Donald Trumps presidential campaign and Russia. But what is a grand jury, how does it work and what does Trump have to fear?

What is a grand jury?

Grand juries are used in only a handful of countries. In the US, they are normally made up of about 16 to 23 members of the public rather than the usual 12, hence grand jury. They are held in secret the fact that one has been convened is not even officially acknowledged. The Wall Street Journal leaked that one has been set up in Washington by Mueller. It will look into links between the Trump team and Russia to influence the White House election and whether there has been any subsequent attempt to obstruct justice.

How serious is this development for Trump?

Potentially huge. The grand jury decides whether a example is strong enough to push ahead with an indictment. But one of the main causes of holding a grand jury is that it is a powerful investigative tool. It can subpoena witnesses and demand the production of documents.

Could Trump be called to give evidence?

Yes. Richard Nixon was called before a grand jury in 1975 over the Watergate case after he resigned as chairman. Bill Clinton was president when he testified before a grand jury into the Whitewater real estate controversy.

Donald Trump Jr and the presidents son-in-law and White House adviser, Jared Kushner, could also be called to testify over their controversial June 2016 meeting with a Russian lawyer.

Why are grand juries dreaded?

Federal attorneys often treat them as fishing expedition. Witnesses can be questioned under oath for hours on end, with investigators hoping to trip them up and stimulate them perjure themselves.

Unlike in ordinary courts, witness are not allowed to have lawyers present. Witnesses have to leave the court to consult with lawyers sitting outside and grand juries are characterised by the time-consuming act of witnesses going in and out.

Lawyers advise witnesses not to be lulled into over-confidence by answering a string of soft questions, and implore witnesses to consult with them before answering even seemingly easy topics. Unlike in ordinary courts, jurors are also allowed to ask questions.

What is the grand jury investigating?

Mueller, appointed special advise in May following the dismissal of FBI director James Comey, has been investigating since May whether members of the Trump team have lied about links to Russians and whether Trump himself tried to obstruct justice. As of yet , no subpoenas have been received by the president or Kushner.

How long will it take for a grand jury to decide if criminal charges should be brought?

Grand juries tend to be slow, running for months or even years.

How has Trump reacted?

He has for months insisted that reports about links to Russia are fake news and told a rally of supporters in West Virginia on Thursday night that theyre trying to defraud you out of the leadership that you want with a fake narrative.

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