In his ruling, Judge Matthew A. Sciarrino Jr. said, “If you post a tweet, just like if you scream it out the window, there is no reasonable expectation of privacy.”
The excerpt is taken from a good layperson’s overview of the case and law that can be found here. The ruling has its genesis in a trespass prosecution connected with the Occupy movement.
Here is a worthy comment on the context of the decision from Natasha Lennard at Salon:
Of course, the lesson to take away is to tweet with caution. It’s also worth keeping in mind that, although throwing up some important insights, this court battle began over a charge for marching on a bridge. As Stolar puts it, “It’s prosecutorial overkill; using a sledgehammer to squash a gnat.” Harris agrees. He is (as he tends to be) disappointed in the state and surprised that a Harvard Law-trained ADA’s time is being used to pursue his minor charge. The precedent set, however, should give pause to those of us who live (perhaps too much of) our lives through Twitter.