A Facebook engineer has publicly chastised Google for snipping Facebook's access to the Gmail Contacts API, accusing the search giant of data-hoarding hypocrisy.

But in doing so, he unloads more than a little hypocrisy of his own.

"Openness doesn't mean being open when its convenient for you," Mike Vernal, a member of the Facebook engineering team, wrote in response to a TechCrunch bloggy thing on the matter. "We strongly hope that Google turns back on their API and doesn't come up with yet another excuse to prevent their users from leaving Google products to use ones they like better instead."

On Friday, Google updated the terms of service for its Contacts API, preventing Facebook and other third-party applications from tapping the programming interface unless they offer something similar. Using Google's API, Facebook has long offered its users the ability to import contact names and email addresses from Gmail, but it prevents them from automatically exporting such data to other sites, including Google services.

Facebook does offer a tool for downloading your "friends list." But you can't download email addresses or phone numbers.

So, as Google changed its terms of service, it promptly severed Facebook's access to the Contacts API. This means that new Facebook users can no longer automatically import contact info from Gmail, though Facebook is offering a workaround. You can still manually download your contacts from Gmail.

In a statement released to the press, Google said it's preventing data from moving between Gmail and Facebook because it believes data should be set free. "Google is committed to making it easy for users to get their data into and out of Google products," the statement reads.

"That is why we have a data liberation engineering team dedicated to building import and export tools for users. We are not alone. Many other sites allow users to import and export their information, including contacts, quickly and easily. But sites that do not, such as Facebook, leave users in a data dead end.

"So we have decided to change our approach slightly to reflect the fact that users often aren’t aware that once they have imported their contacts into sites like Facebook they are effectively trapped."

But with his post, Facebook's Vernal says that in the past, Google's social networking site, Orkut, has treated contact information in much the same way as Facebook. In the fall of 2009, Google prevented Facebook from exporting contact data from Orkut via its Comma Separated Value (CSV) file.

"Less than a year ago, Google issued this statement when they blocked their own users' ability to export their contacts from Orkut to Facebook: 'Mass exportation of email is not standard on most social networks – when a user friends someone they don't then expect that person to be easily able to send that contact information to a third party along with hundreds of other addresses with just one click,' [see quote here]" Vernal says.

"This functionality was not a problem when Orkut was winning in Brazil and India but, as soon as people starting preferring Facebook to Google products, Google changed its stance."

With the Gmail Contacts API, he says, Google has changed its stance yet again, preventing users from easily moving Gmail data to another service. "Openness doesn't mean being open when its convenient for you," Vernal continues.

"On Google's website, dataliberation.org, Eric Schmidt says, 'How do you be big without being evil? We don't trap end users. So if you don't like Google, if for whatever reason we do a bad job for you, we make it easy for you to move to our competitor.' How does limiting user choice honor this commitment?"

According to a source familiar with the matter, Google blocked access to Orkut's CSV file for the same reason it's blocking access to the Google Contacts API: Facebook wasn't reciprocating. That said, this isn't what Google said at the time.

Whatever the case, Google now says that if Facebook reciprocates, it will restore access to the Contacts API, which Orkut syncs with. Google stance – at least today – is that it will let you automatically export your data if others let you do the same.

But Vernal reiterates that Facebook will not allow users to export email addresses to other services, because, well, a social networking service isn't an email service. "Each person owns her friends list, but not her friends' information. A person has no more right to mass export all of her friends' private email addresses than she does to mass export all of her friends' private photo albums," he says.

"Email is different from social networking because in an email application, each person maintains and owns their own address book, whereas in a social network your friends maintain their information and you just maintain a list of friends. Because of this, we think it makes sense for email applications to export email addresses and for social networks to export friend lists."

When we asked Facebook to officially comment on the situation, a company spokesperson pointed us to Vernal's post.

The issue here is that Facebook has what Google wants: a sweeping picture of who knows who on the interwebs. Such a picture would suit Google's efforts to make epic amounts of money with closely-targeted online ads – whatever its commitment to "data liberation." But Facebook is reluctant to give up such information. And not just for reasons of privacy.

Facebook's stance surprises no one. Nor is it surprising that the company is trying to say that although it couldn't possibly give up email addresses, Google should give them up tout de suite. Facebook is fighting hypocrisy with hypocrisy. When two large web outfits are fighting for over your data, that's just the way things work. ®