<p>I think it’s true everywhere that the presumption is against accepting graduates into the same university’s PhD program, and I think it’s true everywhere that it’s only a presumption that can be and is overcome. Certainly if the faculty believes that an undergraduate is really hot stuff, there is little reason not to accept him or her as a PhD student. It may help if one is not applying to go straight from being an undergraduate to being a grad student, but has done something else for a couple of years in the interim. That’s been the pattern for most of the BA (or BS)/PhDs from the same university I know.</p>
<p>Note that telling students that there is a “rule” against doing this can be a good way to avoid conflict with and disappointment for students whom the faculty likes but isn’t prepared to accept into a PhD program.</p>
<p>But maybe it is more than a presumption at Berkeley, or some departments there. I don’t have any institution-specific knowledge, and I have heard similar things about specific departments at other universities (e.g. MIT Physics).</p>