Do not open external links in new windows

A university official who shall remain nameless wrote to me this morning the following sentence regarding our web sites:

it is important that links to external sites appear as a new window

The official claims this is for well-established legal reasons.

When Tim Berners-Lee invented the web in 1991, there were no concept of a link opening in a new page. In fact, the target attribute use to achieve this feat was a W3C recommendation only for a brief time: in HTML 4.0 which was immediately replaced by HTML 4.01. It is worth noting that neither frames nor target attributes are supported in recent versions of HTML (XHTML 1.1).

Let’s add that there are serious accessibility issues with opening new windows and that Jacob Nielsen considers it to be one of the top 10 errors web developers can make:

Even disregarding the user-hostile message implied in taking over the user’s machine, the strategy is self-defeating since it disables the Back button which is the normal way users return to previous sites. Users often don’t notice that a new window has opened, especially if they are using a small monitor where the windows are maximized to fill up the screen. So a user who tries to return to the origin will be confused by a grayed out Back button.

As for legal justifications, there are none.