We currently have the notion of exigent circumstances, that if the police have a lawful reason to enter your house without a warrant (such as believing that someone is in imminent danger) and they find in plain sight in the course of that entry evidence of a crime, it's fair game.
A case like this is how we determine if journalists are allowed to hack into government databases. This precedent will be instructive to future activists regardless of how it turns out.
Which, considering the broad definition of "journalist" here, might mean that we're free to hack anything as long as we publish it.
Would I have the right to hack your web service and leak that data because "journalism"?
And if I get caught hacking something could I simply say that my intent was to publish it?