Tom Hanks Jury Case -- Allegations Of Jury Tampering

The trial in which Tom Hanks was sitting as a juror just came to an abrupt halt after charges of jury tampering surfaced ... TMZ has learned.

During a lunch break Wednesday ... a female member of the L.A. City Attorney's Office went up to Tom in a stairwell and thanked him for his jury service, especially because he's such a big celeb and gladly served.

When the court reconvened today ... the prosecutor disclosed that a member of the City Attorney's Office made inappropriate contact with Tom during a break.

The defense then asked for a hearing to prove prosecutorial misconduct. At that point, lawyers on both sides started talking and a plea deal was cut.

Andrew Flier, the defendant's lawyer (seen above with Hanks after the trial), tells TMZ his client pled no contest to a minor infraction -- disturbing the peace.

The defendant had been charged with domestic violence and faced up to a year in jail. Instead, he got a $150 fine, and that's it.

Flier spoke with us on TMZ Live just a few minutes ago (hear below).

As for Tom, he did not say how he was leaning, but said he was there to "serve justice."