For anyone familiar with Connecticut (or Yale University), the city of New Haven is a great example to provide if pressed for why "safe" is unnecessary. Also, it has a harbor.

This reminds me of Portola's assessment upon seeing the body of water to be named San Francisco Bay. He described it as capable of harboring all the world's navies. It still harbors ships fairly safely.

Cheers,
Tim

"Safe harbor" is also the legal term for a statutory provision which reduces or eliminates someone's liability if they have behaved according to a specified standard. An example is the safe harbor protecting Internet providers from copyright claims if they promptly take down challenged material. "Safe haven" is downright wrong in that circumstance.

I disagree about "haven." I think its metaphorical use has weakened its original meaning. If one writes that a dark alley is a "haven for drug dealers" (and I'm not saying that's a good phrase, but you can imagine reading it), is it necessarily a "safe" place for them, a "refuge," or is it just a place that attracts them?

I don't know, Nick. It seems that a "haven for drug dealers" is a place where they can operate with impunity, and is thus "safe" -- at least for them.

Seeming safe and being safe are two different things. Perhaps I split hairs.

Regardless, the organic definition of "haven" in my head seems to not be dictionary-correct. The descriptivist on my left shoulder is screaming at the prescriptivist on my right.

My ODE gives "place of safety or refuge" as the first definition for haven, followed by "an inlet giving shelter", "a harbour or small port", which one supposes was the original literal meaning.  If harbour is an acceptable definition to the lads in OUP, and if "safe harbour" is allowable, then "safe haven" one feels ought at least not to engender apoplexy.

The ODE gives harbour as, first, a place on the coast where ships may moor in shelter, especially one protected from rough water by piers, etc etc, and, second, a place of refuge.

The metaphorical extension does so little injury to the original meanings of the two words, and those were so close, lthat they seem all to trip along happily together.

Fowler finds a distinction less in the purpose of the haven or harbour and more in the facilities available.  In one of those passages which survive more or less intact into Burchfield's third edition of MEU, and which presumably therefore hold some special canonical truth, we are told the "broad distinction is that a haven is thought of as a place where a ship may find shelter from a storm, a harbour as one offering accommodation ... in which ships may remain in safety for any purpose, and a port as a town whose harbour is frequented by naval or merchant ships." 

You may, as so often, get some comfort from HWF.  Muddy waters, though.  I respectfully suggest you rail no more than is good for your health.