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7.3 Relative clauses

See 7.3 of the Checklist »

A relative clause provides information that relates to a noun or noun phrase.  It can do this in 2 ways:

  • by identifying the noun or
  • by adding extra descriptive details about the noun.

This is a fine part of grammar, but it is also relevant to plain language practice. If you choose the wrong type of relative clause or wrong relative pronoun or wrong punctuation, your readers may get confused. And plain language is all about clarity.

Note, grammarians call these 2 types of relative clause, rather confusingly, defining and non-defining. For clarity, we’ll call them identifying and describing.

Identifying relative clause

An identifying relative clause answers the question “which one?” It identifies a noun or noun phrase (“person”, “food”, and “idea of actually going overseas” in the examples below):

Example 1


He’s no longer the person (who) she first married.

Example 2


The shop doesn’t stock the kind of food (that) I like.

Example 3


It’s the idea of actually going overseas that worries me.

The noun or noun phrase being identified can be any part of the main clause: subject, object, or complement (the bit that comes after the verb “to be”). It is also the subject of the relative clause.

You add the identifying relative clause immediately after the noun (phrase) it defines, without a comma. 

Who or that

For a person (noun or noun phrase), use the relative pronoun who. For things or ideas, use that. You can omit who or that if the context is clear without it (see Examples 1 and 2).

Describing relative clause

A describing relative clause adds extra information about a noun or noun phrase. But this is non-essential information, because you can take it out without harming the integrity of the sentence:

Example 4

Including extra information:

I forwarded the email to my friend, who was not amused.


I forwarded the email to my friend.

Example 5

Including extra information:

Peter, who grew up in the working-class suburbs of Auckland, is now a wealthy and powerful man.


Peter is now a wealthy and powerful man.

Example 6

Including extra information:

You all have opinions about healthy living, which is the topic of my talk today.


You all have opinions about healthy living.

Example 7

Including extra information:

The house, which has been sitting empty for several years, will go to auction next month.


The house will go to auction next month.


As you’ll see from all the examples above, a describing relative clause is always comma-ed off from its main clause. If it appears in the middle of the main clause, it takes a comma at each end. This is the same method as we use for including extra information within brackets or dashes. In fact, brackets are often used in legislation in place of commas – see “Relative clauses in legislation” at the end of this document.

Who or which

In describing relative clauses, use the relative pronoun who for people. Don’t get hung up on changing it to whom when describing an object. Nowadays, whom is an archaic grammatical form – it is perfectly acceptable to use who in most cases. (Read more about who vs whom in 8.10 Avoid archaic language.)

Use which for objects or ideas. Don’t use that – it only applies to identifying relative clauses.

Another way to think about relative pronouns in describing clauses is:

PronounStands for
who and he
and she
and they
which and it
and this
and these

 You can also attach a preposition (positioning word) to who and which – eg, “for who”, “about which”. But the best place for the preposition, in most instances, is at the end of the clause:

Example 8

Modern, plain:

The person (who) you are looking for


The person for whom you are looking

Forget those English-grammar sticklers who say you must never split preposition and pronoun. This is a practice “up with which one will not put” – as Winston Churchill famously mocked some 80 years ago.

When relative clauses go bad

Choosing the wrong one

Returning to Example 7, see how your choice of relative clause type can alter the meaning:

Example 9


The house, which has been sitting empty for several years, will go to auction next month.

This combines 2 separate statements:

  • The house will go to auction next month.
  • (By the way,) the house has been sitting empty for several years.
Example 10


The house that has been sitting empty for several years will go to auction next month.

                (…however the house that has been continuously occupied will be sold privately).

Too many in a sentence

Avoid using more than 1 describing clause in a sentence. Using too many will make for a very long sentence and is more likely to be confusing.

Example 12

Complaints data collected by [the organisation] shows that for those who identified as female and disabled, and who approached [the organisation] on the ground of disability, and who felt they had good grounds for a discrimination case, the most common area of complaint was employment, which accounted for 27% of these approaches, followed by government activity (21%), educational establishments and the provision of goods and services, which accounted for 17% each.

It is not possible to rewrite this very long sentence with fewer relative clauses. It needs unpacking and then reconstructing with a mix of short sentences and bullet-point lists.

Example 13
cross.gif Jane, who is a qualified civil engineer who reluctantly agreed to learn the ropes at her father’s company and (who) then grew its then $3-million turnover to $20 million and (who) was the keynote speaker at the Women in Building and Associated services (WIBAS) breakfast last week, said Mackay was a ripe market.
tick.gif Jane, speaking at the Women in Building and Associated services (WIBAS) breakfast last week, said Mackay was a ripe market. A qualified civil engineer, Jane reluctantly agreed to learn the ropes at her father’s company. She grew its then $3-million turnover to $20 million.

In the plain-language translation, the sentence is rewritten – and restructured more logically – as 3 separate sentences. There’s not a single relative pronoun in sight.


Multiple relative clauses with the same subject can omit the who (or which), but they still function as relative clauses.

However, a 2-part relative clause with the same subject and 2 verbs is manageable, but only if each part is short:

Example 14
tick.gif Peter, who grew up in working-class Auckland and (who) could not afford a university education, is now a wealthy, powerful man.

Note, because the second relative clause has the same subject, you can omit the second who.

Awkward mismatches

Relative clauses are about relating. To be effective, they always come immediately after the person, thing, or concept they are identifying or describing.

When relative clauses drift away from their noun, it can cause major comprehension headaches for readers:

Example 15
cross.gif The 2012 London Olympics were accompanied by the staging in Britain of three plays that featured Eric Liddell, a Scots athlete and member of a missionary family who caused headlines when he refused to run in the 100m heats in the 1924 Paris Olympics which were being held on a Sunday and [who] switched instead to the 400m event in which he won a gold medal.

It was Eric Liddell, not the Paris Olympics, which/who switched to the 400m event. And Liddell who caused the headlines, not his family. And the 100m heats, not the whole 1924 Olympics, that were held on a Sunday. The reader naturally refers back to the last noun used. Given the number of relative clauses here, the reader is forced to unravel the sentence to find out who is the real who.

Here is a sentence that demands too much of the reader. They have to work out which of a number of possible nouns a relative pronoun relates to:

Example 16


Dr Green has agreed to sign a declaration with the Opposition Leader seeking to remove Mr Smith, the 62-year-old son of a former prime minister who has close ties with Australia.


…sign a declaration with the Opposition Leader, who has close ties with Australia. The declaration would seek to remove…


…seeking to remove Mr Smith, who has close ties with Australia. Mr Smith is the 62-year-old son of a former prime minister.


…the 62-year-old son of a former prime minister. Mr Smith senior is known to have close ties with Australia.

What makes the original sentence so confusing is the placement of the relative clause. It is not clear who the relative pronoun relates to. Is it the Opposition Leader, Mr Smith, or Mr Smith’s dad? As you can see above, there are many different ways to write this – depending on who is the real who. In each instance, the who goes immediately after the appropriate person.

Read more about this problem in Mismatched sentence parts, the supporting document for 8.6 of the Checklist.

Relative clauses in legislation

Relative clauses are common in legislation. You may use one with substantive effect by, for example, identifying the legal subject of the rule. You may also use a relative clause with non-substantive effect by adding extra information to help users to understand the legislation.

Example 17

… the Minister of the Crown who is responsible for the Inland Revenue Department …

… under section 10 (which relates to …).

Traditionally, the PCO discouraged drafters from including redundancy in legislation. Redundancy is the concept that repeating the law in different words increases the risk of misinterpretation. For example, a relative clause that adds extra information by partially describing the content of a provision or saying it in a subtly different way may be inconsistent with the provision. And this may create interpretation problems.

The PCO no longer strictly applies a “rule” against redundancy. We recognise that some redundancy – for example, in a description of a cross-reference in brackets – may help users to understand a provision more easily. However, this approach has limits. Non-substantive material can play only a supporting role. You must always ensure that the extra information is accurate, is consistent with the text, and is unlikely to cause interpretation problems.

You also need to clarify whether text has substantive legal effect or is non-substantive. That is, whether a relative clause is identifying or merely describing.

Relative clauses can go wrong in legislation just as easily as in other documents.

In particular, you should consider whether including multiple relative clauses in a provision requires the reader to work too hard. For example, it may be better to move the text that defines a legal subject to a separate provision.

Also, adding non-substantive information is a balancing act. You should avoid adding extra information that compromises overall clarity by making a sentence too long or too complex.

You may be able to use the technique of guidance notes to avoid these problems by moving additional information into a note.


To “avoid compromising clarity” (7.3 of the Checklist), the important points to remember are:

  • Identifying relative clauses are integral to the meaning of a sentence and can’t be taken out.
  • In identifying clauses, use who for people and that for things or ideas.
  • Describing relative clauses can be taken out – especially if a sentence is growing too long – without compromising the sentence’s meaning or structure.
  • In describing clauses, use who for people and which for things or ideas.
  • Describing clauses are bound by commas; identifying ones aren’t.
  • Take care not to mix up the 2 types of relative clause.
  • Always position a relative clause immediately after the thing, person, or concept it identifies or describes.
  • Multiple relative clauses in a sentence make reading difficult.

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