Special counsel Robert S. Mueller III. (Saul Loeb/Agence France-Presse via Getty Images)

Breathless tweets and breaking-news banners notwithstanding, reports that special counsel Robert S. Mueller III has empaneled a grand jury in the ongoing investigation of the Trump campaign and potential Russian collusion are entirely unsurprising. This development isn’t a nothing-burger, but it doesn’t suggest anything we didn’t already know.

Grand juries are how federal prosecutors conduct their investigations. The grand jury has the subpoena power that prosecutors need to compel reluctant witnesses to testify under oath. Grand jury subpoenas are also how prosecutors gather documents such as bank records, emails and corporate papers from entities or people who might not produce them voluntarily.

If a preliminary inquiry suggests there is nothing to a case, prosecutors might never empanel a grand jury. They and the FBI might conduct voluntary interviews, examine readily available documents and determine that no more formal inquiry is warranted.

That quick-look, let’s-move-on scenario was never likely here. It’s been clear for months that the allegations are sufficiently serious to merit a full investigation. And in the world of federal prosecutors, that means using a grand jury.

President Trump dismissed allegations of collusion between his campaign and Russia at a rally in Huntington, W. Va., on Aug. 3. (The Washington Post)

In fact, prosecutors in this probe have been using a grand jury for some time. Grand jury proceedings take place in secret, so there is often not a lot of news about what is happening in the room.

But someone who receives a subpoena to testify or produce documents is not bound by those secrecy rules. They are free to disclose — to the media or to anyone else — that they received a grand jury subpoena or testified in the grand jury. It may be that someone who just received a subpoena contacted a reporter and that has resulted in the “breaking news” stories.

The reality is that any investigation serious enough to warrant the appointment of a special counsel was always likely to involve a grand jury. It was always going to drag on for months. In a case this complex, it takes a long time to investigate the various allegations, subpoena and review relevant documents, and put relevant witnesses before the grand jury. If there are grants of immunity or plea deals to be negotiated, that takes time as well.

Mueller has already hired more than a dozen prosecutors to staff his investigation. Anyone who thought this was going to be over quickly was kidding themselves. The “news” confirms what we already knew.

Finally, it’s important to remember that the existence of a grand jury investigation does not mean criminal charges will necessarily result. Especially in white-collar cases, it’s not unusual for grand jury investigations to close with no charges being filed. The grand jury is the investigative tool that prosecutors use to determine whether charges are warranted – and sometimes the answer is no.

In the past weeks, there have been a number of startling and significant developments in the Russia probe. News that the special counsel is using a grand jury is not one of them.