I hope this isn't too off topic for programming, but I'm sure lots of you would like more information when dealing with clients or managers on this topic. I'm looking for actual usability testing & research into opening browser links in a new window. I'm aware of all the reasons why it's a bad idea, but that's not what I'm looking for. I'm also not looking for 'Jakob Nielson Says so', that won't cut it with my audience.
Cheers.
Murray.
Google was unable to provide me with any research results related to opening browser links in a new window.
I would assume that the answer depends on the context and scenarios. For instance, when browsing the Washington Post online, I like the linearity of the browsing experience with link replacing the content of the current window, but when using Google Docs, I like that the main page opens a new window whenever I choose to create a new document or open an existing document.
You may want to consider convincing the client to perform usability testing to guide the decision.