The man, who is standing there, is her ex-husband. Are these commas needed? Or is it:
The man who is standing there is her ex-husband.
The man, who is standing there, is her ex-husband. Are these commas needed? Or is it:
The man who is standing there is her ex-husband.
If "who is standing there" is a restrictive clause--if it provides information that is necessary to distinguish the subject from others of the same type--you don't use commas. This is the scenario you're probably thinking of.
If, on the other hand, the clause merely provides additional but unnecessary information, it is a non-restrictive clause and should be set apart with commas. For example:
A man just said hello to my colleague. The man, who is standing there, is her ex-husband.
As the subject "the man" has already been distinguished by the first sentence, removing "who is standing there" from the second sentence does not make the subject ambiguous. Therefore, it is a non-restrictive clause, and requires commas.
For more, see When to use “that” and when to use “which”?
Not only are the commas not needed, who is may also be removed:
The man standing there is her ex-husband.
I think that the sentence can be simplified by getting rid of "who is".
Instead writing the sentence as: The man standing there is her ex-husband.
But if you are only looking at the current sentence, the commas are not necessary.
Here you should find everything you need to know about this topic.
– KnightHawk Jun 25 '14 at 17:06