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My brother has a PhD in law.

Must be: PhD, never phd.

AnonymousMust be: PhD

Oxford lists Ph.D. first and makes PhD an alternate form.

Until I looked this up, I had never seen anything but Ph.D.

CJ

We Brits are very sparse with our period in abbreviations.

fivejedjonWe Brits are very sparse with our period in abbreviations.

I agree.

Mr Mrs Ms Dr (British version)
Mr. Mrs. Ms. Dr. (American version)

According to Oxford Online Dictionaries, PhD is the British version; the American way is Ph.D.

tamguatlayAccording to Oxford Online Dictionaries, PhD is the British version; the American way is Ph.D.

I think Oxford detects where you're "calling from" and gives you the listings according to that. I think that's why "Ph.D." was listed first for me.

CJ

CalifJim.I think Oxford detects where you're "calling from" and gives you the listings according to that. I think that's why "Ph.D." was listed first for me.CJ

Oxford Online Dictionaries downloaded on my smartphone has the British and American versions. PhD is found in the British version. After I switched to the American version, I typed PhD, but Ph.D. appear

Muy interesante.

CJ

Both PhD and Ph.D. are correct. Technically, Ph.D. is the "more" correct as the dots show that Ph and D are abbreviations. However, it is now common usage to not bother with the dots. (This is the same as in Mr Smith or Mr. Jones).

AnonymousTechnically, Ph.D. is the "more" correct

Not these days in BrE. PhD is correct. So is PhD. The first of these forms is more common.