Special counsel Robert Mueller is reportedly reviewing President Donald Trump's tweets about Attorney General Jeff Sessions and former FBI Director James Comey to consider whether they help make a case for obstruction of justice or intimidating witnesses, according to The New York Times.
It raises the question whether, and to what extent, a person's Twitter feed can be used against them as evidence.
Most criminal defense attorneys have had an accused client who helped his own prosecution when law enforcement sifted through the client's social media accounts. Social media is a rich source of information; it can contain admissions, threats, photos, video and names of witnesses. It's probably a glimpse of the future that social media evidence is especially useful in juvenile delinquency cases.
An aggravated assault in the parking lot after school used to be a difficult "he said, he said" case for the prosecution. Often now, any attack is captured on several different cellphone photos or videos and uploaded for law enforcement to find.
The same is true of statements made on Twitter. Social media can act as a digital journal, or a record of one's musings or stream of consciousness.
As long as it is "authenticated" as evidence, it will be admitted, and jurors will be able to hear it. They will decide for themselves whether the tweets establish intent, knowledge or other relevant states of mind. They might conclude that the tweets are just puffery, or bravado, and they are not persuasive evidence of anything.
Under the Federal Rules of Evidence, evidence is only relevant and admissible if it is first authenticated. While the rules are silent as to social media, they offer examples of authenticating specific forms of evidence predating social media, such as handwriting, voice identification and phone calls.
Social media presents special problems: A printout of a tweet doesn't establish who wrote it or even if it's an accurate depiction. The metadata contained in social media might be helpful in determining its authenticity, but the metadata isn't what the public sees or associates with the content of the tweet.
For Trump's tweets to be admissible in court against him, a prosecutor would have to first show that (1) the tweets really exist (or existed); and (2) they came from him.
When is a person's tweet from his personal account not his own tweet?
One answer: When someone like his lawyer says he wrote it.
Trump's personal lawyer, for instance, took responsibility in December for a tweet from Trump's account that said for the first time that the president knew his former security adviser, Michael Flynn, had lied to the FBI before he fired Flynn in February 2017.
This defense would normally not work with regular citizens; it might work with the president.
On one hand, the president is less likely to be the author of his own tweets because his image and words are heavily managed by multiple layers of staff. On the other hand, of the three presidents who have been in office since Twitter's launch in 2006, Trump's statements on that platform are more the product of his own unfiltered thoughts than those of any other president.
Not much is known about how the president tweets: Whether he uses a personal iPhone; whether he logs on to an aide's iPhone; or whether he dictates tweets. These would all be relevant inquiries for a defense attorney attacking the authenticity of tweets in court. After all, it's not fair to introduce words against a person if there's insufficient evidence that the person actually spoke those words.
Ultimately, the admissibility of the tweets puts the evidentiary cart before the horse. Federal prosecutors don't need the tweets to be admissible evidence for investigative purposes. The information they contain will help them build an investigative timeline. Or they might use them as leverage against a reluctant witness — especially a person identified in the tweet as someone with knowledge.
Trump is learning a lesson that is learned every day in juvenile delinquency court in the United States: Your social media account is your own repository of evidence against you, which the government can borrow at any time to convict you.
Danny Cevallos is an MSNBC legal analyst. Follow @CevallosLaw on Twitter.