7.13 The Comma, General

The comma is the most frequently misused punctuation mark, and many of the rules governing its use are vague and riddled with exceptions. The writer must frequently rely on personal judgment and should be guided by considerations of clarity more than by any particular set of rules.

Note that, as a general rule, commas interrupt the flow of a sentence and should therefore not be used where they do not contribute to clarity. A sentence requiring a large number of commas for clarity is probably a poorly constructed one in need of rephrasing. Yet the comma is also the mark most often incorrectly omitted.

7.14 Restrictive/non-restrictive

Most difficulties with the use of the comma hinge on the distinction between restrictive and non-restrictive sentence elements. A restrictive word, phrase or clause adds to the words it modifies a "restrictive" or defining element that is essential to the meaning of the whole; it should therefore not be separated by a comma or other mark of punctuation. A non-restrictive element provides incidental or supplementary information which does not affect the essential meaning; it should be set off by a comma or commas.

Compare

• The senators who had objected most strongly to the shift in policy were quick to acknowledge the error in their thinking. (restrictive)

and

• The senators, who had objected most strongly to the shift in policy, were quick to acknowledge the error in their thinking. (non-restrictive)

(a) Introductory elements

There are exceptions to the general rule for punctuating restrictive and non-restrictive elements. An introductory phrase or clause, especially if it is a long one, is often followed by a comma even if it is restrictive:

• Of all election issues, the place of minorities in society is the most sensitive.
• When choosing between two approaches, it is important to consult experts in the field.

but

• In the course of the conference some provincial leaders reversed their position on Native rights.

Each of the above sentences could have been correctly punctuated with or without the comma. But an introductory subordinate clause is normally followed by a comma:

• If you can’t log on the Web site, then call the technical help desk.
• Now that the Canadian film industry has come of age, it is time to focus on securing a larger share of the market.

After introductory adverbs and short phrases indicating time, frequency, location or cause, the comma is omitted unless needed to avoid ambiguity or add emphasis:

• By next week the new budget will have been thoroughly analysed.

but

• In 1994, 1457 employees started using the new operating system.

Introductory adverbs or phrases used to mark transition or to express a personal comment are usually set off by commas:

• Nevertheless, the program will go ahead as scheduled.
• In short, no hiring is currently taking place.

The introductory phrase may also consist of an adjective or participle separated from its noun by the definite or indefinite article:

• Unprepared, the team was no match for its opponents.
• Clearly upset by the heckling, the speaker stopped for a moment to regain his composure.

Conversely, it is sometimes possible to omit the commas that ordinarily set off non-restrictive elements, without obscuring the meaning. This is especially true of short adverbial expressions:

• Her words went of course unheeded.
• All the same he had no compunction about slipping the waiter a few dollars to be on the safe side.

In such sentences the addition of commas not strictly needed for clarity gives emphasis to the elements thus enclosed:

• Her words went, of course, unheeded.

(b) Absolute expressions

One form of non-restrictive expression is the absolute¹ construction: a participial phrase grammatically unconnected with the rest of the sentence. Such phrases are followed by a comma:

• Weather permitting, the conference will be held as planned.
• The chapter completed, I returned to my former duties.

Note the following errors in the punctuation of absolute expressions:

• The investigation had been completed, and the results, having been known for some time, the public was anxiously waiting for heads to roll.
  (remove comma after results)
• We were unable to answer her questions. The truth being that we hadn’t given the matter much thought.
  (replace the period after questions with a comma or dash)

___________________

(c) Parenthetic expressions

Parenthetic expressions are non-restrictive and therefore require commas:

• We could see that the plan, if not actually rejected out of hand, was far from popular with senior management.

If a parenthetic expression is removed from the sentence, the remainder of the sentence should read as a coherent, grammatically correct whole. For example, the sentence

• The task force wanted to show that it was as good, if not better, than its predecessors.

is unacceptable because "as good . . . than" is incorrect English. The sentence should be recast as follows:

• . . . it was as good as, if not better than, its predecessors.

Occasionally it may be expedient to omit the first of the pair of commas around a parenthetic expression:

• But without realizing it, he had sparked a whole new controversy.

The parenthetic phrase here is "without realizing it."

Both commas can sometimes safely be omitted; under no circumstances, however, should the second comma be omitted while the first is retained:

• But without realizing it he had sparked a whole new controversy.

not

• But, without realizing it he had sparked a whole new controversy.

Parenthetic expressions may be set off by parentheses or dashes instead of commas, depending on the degree of emphasis or pause desired, or the length of the expression. Compare:

• Jane (evidently) had no stake in seeing the dispute continue.
• Jane evidently had no stake in seeing the dispute continue.
• Jane, evidently, had no stake in seeing the dispute continue.
• Jane—evidently—had no stake in seeing the dispute continue.

A common error occurs with parenthetic phrases following the conjunction that. The comma that belongs after the conjunction is often placed before it instead:

• The odd thing was, that no matter how he tried, he couldn’t remember where he had left the document.

(d) Appositives

Restrictive and non-restrictive appositives should be carefully distinguished. The latter are set off by commas, whereas the former are not:

• St. John of the Cross
• Graham St. John, of Hoary Cross
• Her painting Reflections drew a poor response from the public.
• Her first painting, Contrasts, has been little studied.

As in the case of parenthetic expressions, the comma following a non-restrictive appositive cannot be omitted. Thus the sentence

• The statement by the Government House Leader, Herb Gray that no changes would be made to salaries paid to Parliamentarians was not unexpected.

is incorrect. A comma is required after "Gray."

Non-restrictive appositives in final position are usually preceded by a comma:

• Our supreme governors, the people.

Often, however, the comma is replaced by a colon or dash:

• Tact: a quality that no skilled diplomat can do without.
• Margaret Laurence—perhaps the greatest writer to come out of Manitoba.

If the appositive contains internal commas, it is best introduced by a mark other than the comma. In the following example, a colon would be an improvement over the comma after legacy:

• The Pearson government left behind a remarkable legacy, a pension plan, a universal medicare plan and a new flag.

(e) Annunciatory expressions

The annunciatory expressions namely, that is and for example are usually followed by a comma. They may be preceded by a comma, a dash, a semicolon or a period, or, together with the matter they introduce, may be enclosed in parentheses, depending on the emphasis desired:

• Plans for Senate reform should be honestly and objectively assessed, that is, bearing in mind only the public good.

The abbreviations i.e. and e.g.—although these are identical in meaning to that is and for example—should be preceded by a comma, a dash or an opening parenthesis, but need not be followed by a comma.

Note that the expression such as is used to introduce an example, not an appositive, and therefore is not followed by a comma. It may be preceded by a comma or other punctuation, as required in the sentence.

(f) Vocative forms

Vocative forms are non-restrictive and are set off by commas:

• Gentlemen, where I come from, a black-hearted bastard is a term of endearment.
  —Donald Gordon
• Awake, my country, the hour is great with change!
  —Charles Roberts

Similarly, exclamations and interjections are set off by commas (or exclamation marks):

• God, what a lot we hear about unhappy marriages, and how little we hear about unhappy sons and daughters.
  —Robertson Davies

7.15 The Comma, Co-ordinate elements

Elements of equal rank or relation in a sentence are said to be co-ordinate. The co-ordinate elements may be words or phrases in a series, or they may be entire clauses.

(a) Nouns and noun phrases

Items in a series may be separated by commas:

• Complacency, urbanity, sentimentality, whimsicality

They may also be linked by co-ordinating conjunctions such as and or or:

• economists, sociologists or political scientists
• the good, the bad and the ugly

Opinions differ on whether and when a comma should be inserted before the final and or or in a sequence. In keeping with the general trend toward less punctuation, the final comma is best omitted where clarity permits, unless there is a need to emphasize the last element in the series. This comma is usually omitted in the names of firms and always before an ampersand:

• Deeble, Froom & Associates Ltd.
• Cohen, Hansen and Larose

On the other hand, it is usually inserted if the items in the series are phrases or clauses of some length, or if omission of the comma might lead to ambiguity or misunderstanding:

• Tenders were submitted by Domicile Developments Inc., East End Construction, Krista, and Ryan and Scheper.

A comma is also required before etc.:

• He brought in the wine, the glasses, etc.

A more complex situation occurs when apposition commas are used together with co-ordinating commas, as illustrated below:

• Carla Tavares, a recent MBA graduate, three students and a technician set up the experiment.

The sentence should be rephrased so that no non-restrictive appositive occurs within a co-ordinate element:

• A recent MBA graduate named Carla Tavares, three students and a technician set up the experiment.

Alternatively, semicolons may be used to separate elements in a complex series (see also 7.23 The Semicolon, Co-ordinate elements):

• Jane Stewart, MP for Brandt, Ont.; Stan Keyes, MP for Hamilton West, Ont.; John Nunziata, MP for York-South Weston . . .

(b) Clauses

A comma is normally used to separate two main clauses in a compound sentence when they are joined by a co-ordinating conjunction (and, but, or, nor, yet or for):

• They are often called individualists, and in economic matters they were, but in social matters, the dominating concept was that of good neighbourliness.
  —M. M. Fahrni

If the clauses are short or closely related, the commas may be omitted before and, but, or or nor:

• He opened the letter and then he read the contents.
• Life is short but art is long.

Co-ordinate clauses not joined by a co-ordinating conjunction are usually separated by a heavier mark of punctuation than the comma:

• When the white men came we had the land and they had the Bibles; now they have the land and we have the Bibles.
  —Chief Dan George

A comma will suffice, however, if the clauses are short, or if the writer wishes to emphasize a contrast or lead the reader on to the following clause as quickly as possible:

• There are good regulations, there are bad regulations.
• It was not the duration of the pilot project that caused concern, it was the size of the project team.

When a number of independent co-ordinate clauses follow one another, a comma should be used after each one except (usually) the last, in accordance with the rule for items in a series (see 7.15 The Comma, Co-ordinate elements(a)):

• She investigated the matter, wrote a report, presented it to the committee and answered everyone’s questions satisfactorily.

It is a common error to confuse a simple sentence having a compound predicate with a compound sentence requiring a comma between clauses. Note the difference between the following examples:

• She investigated the matter and then wrote a detailed report.
  (simple sentence)
• She investigated the matter, and then the committee began its work.
  (compound sentence)

Where the clauses of a compound sentence are joined by a conjunctive adverb (such as however, instead, meanwhile, otherwise, similarly, so, still, then, therefore or yet), a semicolon is usually called for, though a comma will often suffice before so, then and yet:

• Much of English-speaking Canada has been populated . . . by a highly literate people, drawn in part from the educated classes of the Old Country, yet in its two hundred years of existence it has produced few books and not a single great one.
  —E. A. McCourt

(c) Adjectives

A series of adjectives modifying a noun may or may not be co-ordinate. The adjectives are co-ordinate if their order does not affect the meaning, in which case they should be separated by a comma. If they are not co-ordinate, that is, if one adjective modifies the phrase formed by the following adjective(s) plus the noun, then they should not be separated by a comma:

• a rich, creamy sauce

but

• a naive domestic burgundy

Adjectives of both types may of course occur together:

• a tender, succulent young chicken

The rule stated above, however, is not an infallible guide. When in doubt omit the comma, as in:

• The plain honest truth is that he is a liar.

The final adjective in the series should not be separated from the following noun by a comma:

• Nations require strong, fair, open, decisive government.

(d) Antithetic expressions

Antithetic expressions are usually separated by a comma:

• This proposal is not to be tossed lightly aside, but to be hurled with great force.

However, short expressions of this type may not require a comma:

• The more wit the less courage.

7.16 Clarity and emphasis

Sometimes the reader will be led astray by a word or phrase which appears at first to be used in one sense but turns out from the context to be used in another. In all the following examples, commas should have been used in order to prevent misreading:

• In all his efforts were quite laudable.
  (comma after In all)
• He was taken to the cleaners and left without any money, he soon grew desperate.
  (comma after and)
• In the presence of Sir Henry James began to quiver.
  (comma after Sir Henry)
• I was high up and far below I saw the globe of the earth.
  (comma after up)

The comma can be a useful device for securing a pause or emphasis:

• I am sure the contract will be signed, eventually.
• Senior management had, once again, put itself in a no-win situation.
• The end had come, but it was not yet in sight.

7.17 Omitted words

A comma may be used to indicate that words have been omitted:

• The African countries sent six representatives; the Asian countries, five.

Again, the comma may be omitted if clarity is not compromised.

See also 7.22 The Semicolon, Between independent clauses and 7.23 The Semicolon, Co-ordinate elements.

7.18 Quotations, etc.

Place a comma after words introducing short direct quotations, declarations and direct questions (a colon is needed to introduce longer sentences):

• A politician once remarked, "Life is short; live it up."
• I repeat, No milk today.
• Ask yourself, Can I afford this?

Note the capital letter and the absence of quotation marks in the last two examples.

If the quotation or question follows a form of the verb to be, is in apposition to a noun, or is worked naturally into the syntax of the sentence, no comma is needed:

• What he actually said was "Play it, Sam."
• Did I give a satisfactory answer to the chairperson’s question "Why are there so few women in management?"
• She asked us to "rephrase the question to make it less offensive."

It is also acceptable to omit the comma before quotations introduced by verbs of saying:

• He said "Have a nice day," fired a few shots, and ran.

The use of punctuation in quotations is discussed in 8.03 Punctuation and grammar in run-in quotations.

7.19 Names and titles

Commas are used around titles and degrees within the body of a sentence:

• Charles Peabody, MD, PhD, was the first to arrive.
• Judith Foster, Chairperson of the Foreign Affairs Committee, made the opening statement.

A comma is placed between a surname and a given name or initials if the surname is written first:

• Mammouri, Muhammad
• Grove, F. P.

Chinese and Vietnamese names are an exception. They are written with the family name first and no comma:

• Deng Xiaoping
• Nguyen Tranh

7.20 Dates, geographical names and addresses

Use a comma to separate the day of the week from the date and the place from the date:

• Friday, February 13 but Friday the thirteenth
• Hull, February 13

If the date is written in the order day-month-year, no commas are required before, after or between the components of the date:

• The meeting of 10 January 1996 did little to allay tensions.

If, however, the order given is month-day-year, the day and year are separated by a comma, and the year should normally be followed by a comma within the body of a sentence or sentence equivalent:

• February 20, 1995, marked the beginning of a new era.
• On April 16, 1985, certain additional provisions of the Charter took effect.

If you are stating only the month and the year, do not insert a comma:

• Treasury Board approved the submission in February 1995.

Similarly, a comma separates a place name from the name of a province or the abbreviation for that province, and the province’s name or abbreviation is normally followed by a comma within the body of a sentence or sentence equivalent:

• Swift Current, Saskatchewan, has applied to host the event.
• We arrived at Corner Brook, N.L., the following day.

Use commas to separate address components, as illustrated:

• Our address is 340 Laurier Ave. West, Ottawa, Ontario  K1A 0P8, and our telephone number is 613-999-9900.

Note that the postal code is followed, but not preceded, by a comma when the address forms part of a sentence, and that two spaces separate the provincial name from the postal code.

7.21 Commas properly omitted

Do not use commas between the name and the number of an organizational unit:

• Teamsters Union Local 91
• Loyal Order of Moose 1765

Do not insert commas in numerical expressions such as the following:

• 2 years 6 months 7 days
• a 2-year 6-month sentence
• a 3-minute 50-second mile
• 1 h 12 min 55 s

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