I have been proofreading and editing articles written by lawyers for the past 25 years. Lawyers are very fond of long sentences. Often these contain numerous phrases starting with which.
Not only are these long sentences difficult to read and can often be split into two or three shorter ones, but many times the word which is used instead of that. They are not interchangeable – each has its place. Let me explain.
Which or that
That introduces essential information (also called a restrictive clause). Without it, the sentence doesn’t make sense.
- Example: The house that I want to buy is in a state of disrepair. When shortened to “The house is in a state of disrepair” the context is missing. The fact that it’s the one I want to buy is the point of the sentence. Wrong would be: The house which I want to buy…
Which is used for optional information (also called a non-restrictive clause). It is added between commas and can be removed without the sentence losing its meaning.
- Example: The house, which is in an established suburb, needs work before I can move in.
The information about the suburb is not that relevant, so the phrase between commas could fall away.
When deciding whether to use which or that, ask yourself whether the phrase you’re adding is disposable (use: which) or essential (use: that).
Better without “which”
Although non-restrictive clauses (those with which between commas) have their place, often sentences can be split in two, making them more reader-friendly.
- Correct use of which:
His rude and obnoxious behaviour, which explained why he didn’t have any friends, usually brought out the worst in people.
But even better would be doing away with the non-restrictive clause and rather tell the story in two sentences: His rude and obnoxious behaviour usually brought out the worst in people. His disagreeable nature also explained why he didn’t have any friends.
- Correct use of which:
A financial adviser took out a professional indemnity policy, which was meant to indemnify him against legal liability.
Better writing: A financial adviser took out a professional indemnity policy meant to indemnify him against legal liability.
Even better: A financial adviser took out a professional indemnity policy as protection against legal liability.
Which has its place, but often you can do without it altogether.
Who versus that
Who is used for people and that for things. Although it’s not wrong to use that for people occasionally, it makes sense to use who when possible, simply because the word that is used so often.
Marie Curie was the first woman who won a Nobel Prize.
The SPCA is an organisation that cares for homeless animals.
In case you’re interested
Who, which and that are called relative pronouns. A relative pronoun is used to connect a clause or phrase to a noun or pronoun.