A while ago, there was a case where Boeing (a defense company) accidentally sent details of its new in-development aircraft to Lockheed-Martin (a competitor). It contained blueprints and plans on the aircraft, as well as planned marketing/development costs, planned release dates, and so on.
This information was not intended to be released to Lockheed-Martin. What are Lockheed-Martin's rights concerning this information? Can they read it? If so, why so? If not, why not?