The New Hampshire Bar Association Ethics Committee issued an Opinion on the "Disclosure, Review and Use of Metadata in Electronic Materials" (hat tip to New Hampshire attorney Bruce Dorner). New Hampshire is the latest in a growing number of states issuing opinions on the thorny issue of what is and is not permissible with respect to using metadata.

Metadata, in case you are unfamiliar with the term - and a lot of attorneys still are, is data that is inadvertently left behind in electronic documents that can reveal potentially confidential information, such as prior edits. There is a helpful and highly readable article on metadata and ethics written by Jim Calloway that will bring you up to speed quickly.

The New Hampshire Bar Association Ethics Committee opined, in short:

• Lawyers sending electronic information must take reasonable care to avoid disclosing confidential information through metadata
• Lawyers receiving electronic information from opposing counsel have an ethical obligation not to search for, review, or use metadata containing confidential information 

In essence, the Committee comes down on the side of protecting the senders of metadata. I'm not sure I agree with the underlying policy, but if you practice law there at least you know where you stand.