Google is all for data portability, unless it threatens the company's dominance of online advertising.

In a report published last week, Harvard business professor Benjamin Edelman takes Google to task for imposing on its advertisers restrictions that make it difficult for them to use competing ad platforms offered by Microsoft and Yahoo.

The issue is that the Google AdWords API terms of use restrict advertisers from copying ad campaign data to competing platforms. Sure, you can move your AdWords campaign data to Microsoft AdCenter, but doing so requires a 17-step process.

"By encouraging small to medium-sized advertisers to advertise only with Google AdWords, Google's API restriction reduces the number of advertisers using competing ad platforms," Edelman writes. "This harms competing platforms in two distinct ways. First, it reduces competitors' coverage -- preventing competitors from featuring relevant ads that pertain to obscure user searches. ... Second, by reducing the number of advertisers bidding for advertising positions at other platforms, the quoted provision dramatically reduces revenue at those platforms."

Edelman also says that Google's API restriction reduces the value of advertising inventory held by third-party publishers.

Google, which is usually very good about responding to requests for comment, has not yet gotten back to me to explain its position. That may be because there really isn't a good way to explain how it can support data portability for user data and social network data while opposing data portability for ad data.

As Edelman points out, the AdWords API restrictions contradict Google CEO Eric Schmidt's assertion that "we would never trap user data." Certainly, Google could argue that user data is different from ad data. But Google has consistently supported "data portability" without any qualifying adjective.

Google should do the right thing and compete by offering superior technology instead of by making it more difficult for advertisers to work with competitors.

Update: After this post was published, Deanna Yick from Google did indeed respond. In an email, she said:

Thanks for reaching out. Please note that the section of our Google AdWords Terms and Conditions that Ben Edelman cites does not apply to End-Advertiser-Only AdWords API Clients. In other words, it does not apply to individual advertisers, as they are free to take their data and do with it what they want.

Rather, the restriction applies only to third parties and is part of our co-mingling policy. The spirit of this section is that we want our third party developers to expose the full functionality of AdWords to their advertisers - thus the prohibition against co-mingling data and copying data fields, which we think can lead to misleading comparisons (e.g. the way Google counts impressions/clicks may not be the same as on another advertising platform.) If AdWords data is combined with data from other sources, that could lead to inaccurate comparisons of data and make it difficult for the end advertiser to understand the performance of AdWords relative to other products.

The language of our Terms and Conditions makes it quite explicit that the section in question does not apply to our advertisers -- so if an advertiser is writing an API application to manage his or her own advertising on Google, he or she is welcome to do so. This is not an issue of data access for users. In fact, we allow easy export as any advertiser can also use our free tool, AdWords Editor, to download their full campaign structure at anytime, and export to csv, html and the Google file format.

In addition, Yick said:

Specifically, I'd like to clarify that the statement in your story that says "The issue is that the Google AdWords API terms of use restrict advertisers from copying ad campaign data to competing platforms" is not accurate. The section of our Terms and Conditions being referenced only applies to third parties as part of our co-mingling policy and does not apply to individual advertisers who are free to take their data and do with it what they want (either through the AdWords API or through the AdWords Editor).

In an email, Benjamin Edelman responded:

Seems like that response completely misses the point. See my article, section "Google's response", first bullet point and its two sub-bullets.

To typical small to medium-sized advertisers, it's not useful to be told they can write their own API tools. These advertisers want pre-written off-the-shelf tools to help them do what they want to do. Instead, Google asks them to reinvent the wheel by writing their own code.

The "comingling" rationale doesn't ring true either. If Google's true concern is comingling, then there's no reason to prohibit simple one-way export. Yet that's exactly what Google's policy specifically and directly prohibits. Recall: "the AdWords API Client may not offer a functionality that copies data ... from an AdWords account to a non-AdWords account."

That's not a restriction on comingling. That's a restriction on export.