As far as l know, it is usual to use a comma after a modified noun followed by a non-restrictive relative clause as follows:

The new AIDS treatment, which proved to be highly effective, is extremely expensive.

My question is: Are there special cases that we might ignore using the comma in constructions as the one mentioned above.

  • It's the comma that marks the relative clause as supplementary (non-restrictive). Removing it would make it an integrated (restrictive) relative. You, Mido Mido, have to decide which semantic type of relative it is before deciding whether or not to use a comma. – BillJ Dec 31 '17 at 18:50

To a careful reader, your example, with a pair of commas, is a non-defining relative clause. Consequently, it can be removed and the sentence would both still remain grammatically correct and its meaning wouldn't change.

If a sentence contains an adjective clause introduced by the relativizer which, a careful writer would firstly determine whether the subordinate adjective clause is defining or non-defining and would use commas or not accordingly.

The use of the relativizer that is different. Usually we don't use a comma before it.

| improve this answer | |
  • Yes, the writer must decide whether the relative is semantically integrated or supplementary in order to decide whether or not to use a comma. Btw, it is extremely rare to find a supplementary relative with that. In fact they are only marginally acceptable in Standard English. – BillJ Dec 31 '17 at 18:59
  • @Bill J ls there a difference between"The red car which you chose was sold" and " The red car, which you chose, was sold"? – Mido Mido Dec 31 '17 at 20:13
  • @MidoMido Yes, If there was more than red one car and you chose one of them, then the restrictive relative clause is required - the kind without a comma. But if there was only one red car, then the clause is non-restrictive and a comma is required. The relative clause in this case simply adds useful, but non-essential information. – BillJ Jan 1 '18 at 7:41

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.