Having been approached by the source,
one has to decide whether the information is relevant, but more importantly, whether it can be used.
One has to consider the libel laws of course.
Very tricky, here's an example:

SOURCE: I am a confidant, and advisor to politician A.
Politician A. did not have the necessary funds to run for a seat,
so we bribed a few people, we showed the party that he could "work" the system for votes.
The party leader was so impressed, that he was awarded a position on the slate.
My reward will be a plumb position, when the party is in office.
It's okay, what we're doing, our opponents do it too, it's just that we offered a little bit more money.

The tale doesn't just implicate the politician, and his staff.
The source is also implicating the party leader, and pretty much condemning not just his party, but himself, and anyone else close to politician A.

Question: If the source is verifiable, and is who he claims to be, which is a confidant and close adviser,
should that be enough to publish the article?

Was it Judith Miller, the New York journalist who was imprisoned for not disclosing the source of the Valerie Plame leak?

Turns out the source was "Scooter" Libby, the Vice Presidents top "man Friday", and doer of dirty deeds.
He was charged of course, but as they were leaving the courtroom after his conviction, his wife, in anger yelled out to the packed hallway,"We're gonna fuck 'em all"!

Shortly thereafter, George W. Bush, commuted his sentence, and one of the few pardons he granted was to "Scooter Libby".
Every country is different, when it comes to laws about what's considered libelous, or scandalous.
That's the reason American stars tend to sue British tabloids for libelous content. It's easier to prove in a British court of law malicious intent by the author or the article, or the person responsible for releasing the video, photograph etc.

B.S. a local journalist was forced to retract certain articles several weeks ago, under the threat of a lawsuit.
What made her article libelous? Was it the source of the information? Or lack of physical proof?

In court, who would the onus, or burden of proof be on? The public figure, or the author?

Nobody should be subjected to lies be published about them online, or anywhere else, and if a story is extremely inflammatory, then
the source can't be just any old Joe Schmoe from down the street.
I would love to ask Roland Duncan about "malicioua intent" laws in St Maarten and the Antilles.
Mr Duncan is a politician, but also an attorney.
And this is just an example of source verification: If I were to be fed incriminating or inflammatory information about him from a source who was very close to him e.g. a family member, or staff, as a lawyer, how would he deal with the issue?
Would the onus be on the author, the source, or Mr Duncan?

I guess in time, I'll return to this little topic, but what I'm getting at is.....
having described a "fictitious" source and "Politician A." above,
would I write the story, since it is would be relevant to the upcoming elections,
or should I sit on it, out of respect for the politicians involved, or out of fear?