Quite a few students get confused about how they can use these phrases (‘should’, ‘ in case’ and ‘ happen to’) all together, or in pairs or even on their own! I think the fact that they are so flexible only adds to the confusion!

In total there are 9 combinations, although there are differences in usage.

Basically all combinations are possible, but the order, within a single clause, is always:

So for example :

However, this sentence means the same as all of these…

IN CASE + SHOULD
• (2) In case there should be a problem, call me*.
IN CASE + HAPPEN TO
• (3) In case there happens to be a problem, call me*.
SHOULD + HAPPEN TO (with ‘if)
• (4) If there should be a problem, call me*.
SHOULD + HAPPEN TO (with inversion)
• (5) Should there happen to be a problem, call me*.
And even individually;
• (6) In case there is a problem, call me*.
• (7) If there should be a problem, call me*. (should with if)
• (8) Should there be a problem, call me*. (should with inversion)
• (9) If there happens to be a problem, call me*.

Which expressions do we use ‘most’ today?

So of the 9 expressions, I think there are some which just seem very dated indeed, and a couple more which are much more common – leaving a few in the middle, which are used as a personal choice (I use (8) more commonly than most people, for example).

Firstly, in modern English almost all usages of ‘should’ other than giving advice (‘You should do that’) are becoming less common. I will come back to this below because it also depends on geographical differences, but the trend worldwide is there.

So the following I would consider dated, or at least semi-formal, in modern English:

• (1) In case there should happen to be a problem, call me*.
• (2) In case there should be a problem, call me*.
• (4) If there should happen to be a problem, call me*.
• (5) Should there happen to be a problem, call me*.

And the next two, the simpler forms of using ‘should’ alone, are little more common - but many would find them not very modern.

• (7) If there should be a problem, call me*.
• (8) Should there be a problem, call me*.

I will return to these phrases using ‘should’ later, when I look at some differences between British English and American English. But for now let me just say that ‘should’ is used much more commonly in some English speaking areas (like the UK) compared to others (USA, for example).

[I wrote a blog post on using IF + SHOULD here, should you be interested!]

I think in modern English there is a tendency for simpler more direct phrases and now the most common formats would be the simplest usage of ‘in case’ and ‘happen to’ on their own:

• (6) In case there is a problem, call me*.
• (9) If there happens to be a problem, call me*.

The sentence (6) while very simple, does have some controversy though and we will look at this when we compare the logic of ‘in case’ to ‘if’ below.

That leaves the last phrase, the combination of ‘in case’ and ‘happens to’:

• (3) In case there happens to be a problem, call me*.

I wouldn’t consider this sentence as direct as (6) or (9) but it is still used.

If I had to choose one sentence that is both modern and least likely to create any confusion, I think the winner would be < <...drum roll...> >

• (9) If there happens to be a problem, call me*.

"Happen to" Vs. "Should" : British and American Usage Over Time

In general ‘should’ was used much more frequently than now, and even more frequently in the UK.

For example (as Swan [2] points out),

There is another difference between BrE and AmE when we consider In case and If….

Differences between ‘IN CASE’ and ‘IF’

There is a difference in the usage of IN CASE and IF, especially between American English and British English.

Swan [2] states:

And he continues with some more examples:

Compare:

• Let's buy a bottle of wine in case George comes. (= Let’s buy some wine now because George might come later.)
• Let's buy a bottle of wine if George comes. (= We’ll wait and see. If George comes, then we’ll buy the wine. If he doesn’t, we won’t.)
Two more examples of 'in case' being using for a subsequent event [BrE & others];
• I’m taking an umbrella in case it rains. (So later I can use the umbrella if it rains.)
• People insure their houses in case they catch fire. (So after there is a fire they can then claim damages, they are not insuring their house just as it starts to burn! People telephone the fire brigade if their houses catch fire.)

And he then goes on to show the differences to American English.

In American English, in case is often used in a similar way to if.

Or in a different wording Carter & McCarthy [1] state:

So what about ‘in case’ and ‘if’ with ‘should’ and ‘happen to’, what happens if we change ‘in case’ with ‘if’?

• (1) In case there should happen to be a problem, call me*.
• Becomes (1b) “If there should happen to be a problem, call me”

Personally I think that sounds even better! But the difference in meaning between the two sentences is very similar, I mean...How can I call you now because there is a risk of a problem later! I have to wait until I actually have a problem first!

(And this is true for sentences (2), (3) and (6) – if ‘in case’ is swapped with ‘if’ there is no change in meaning.)

But what if I change (1) to: (1c) In case you should happen to meet John, call me.

But even these might not be clear about which happens first “call” or “meet John”.

So look at the ubiquitous rain and umbrella example:

• “In case it should happen to rain (later), take an umbrella”
• “Take an umbrella, in case it should happen to rain (later)”

&

(Again this would be valid for the sentences (2), (3) and (6))

There is a difference between (1c) and (1d) for most speakers. Can you see what it is?

The sentence (1d) has the following logic;

• “In the future, if you meet John, can you call me please?”
But sentence (1c) for many speakers of English means;
• “Can you call me now? Because there is a risk you might meet John in the future and I need to tell you something so you are prepared.”
However, for some speakers they will understand the sentence to mean the same as (1d). Crazy!

So, how can you tell the meaning? Well, I think context and common sense will help a lot, and just being aware that some people ‘interpret’ “in case” differently will help!

Extra Notes

Using Just

We can add ‘just’ to ‘in case’ and this adds EXTRA uncertainty about the event actually happening!

It means: I do not think it is likely that it will rain.

As Mccarthy states: “In case is frequently premodified by just, indicating that the speaker thinks the outcome is unlikely:

In Case + Subjunctive

“In case he were to come I decided...”

If you have come across this structure it is possible you are reading an old novel!

As Mccarthy states:

"In case may, in very formal and literary contexts, be followed by the subjunctive form were to:

This form is not particularly used nowadays – unless you want to write an authentic historical drama perhaps!!

When SHOULD comes before IN CASE!

I said before that the order is: IN CASE before SHOULD before HAPPEN TO.

But what about a sentence like this: “You should call me, in case there happens to be a problem.” or “You should call me, in case you happen to meet John.”

Here the ‘should’ is actually a different clause and simply means ‘it would be best / I recommend’. So you are giving some advice about the ‘in case’ clause (and not further describing it) – they are separate clauses.

Technically, you could even write:

But really in modern English ‘should’ has become so less used nowadays that this over use of ‘should’ makes you seem you have time-travelled from the year 1924.

Can we use SHOULD in a past situation with IN CASE?

So if we take this sentence with a present/future meaning:

• “In case you should have a problem, call me.” (In case = Reaction)
• “Take an umbrella, in case it should rain.” (In case = Precaution)

What happens if we want to talk about a Past Situation?

Well, when we use a modal in the past we often use it in the Perfect Aspect:

• “In case you should have had a problem,...”
• “...in case it should have rained.”

But the other clause needs to be different in the two cases, we cannot use an Imperative in the past – it makes no sense to tell someone what to do yesterday.

And, what do we use to tell people what they should have done? Well ‘should’ of course!

So we get the following ‘advice’ in the past:

• “...you should have called me.”
• “You should have taken an umbrella...”

But now we have ‘should’ twice in the same sentence!

Stylistically this is not great, and in this case we would remove the ‘in case + should’ (and simply make them in the Past), giving the following two final sentences:

• “In case you had a problem, you should have called me.” (I would even prefer the clearer, “If you had a problem…”)
• “You should have taken an umbrella in case it rained.”

Related Questions

What is the Difference between “In case” & “In case of”

Both ‘in case’ and ‘in case of’ carry the idea of ‘if’.

The Cambridge Grammar of English [3, SECTION 755] states it as:

So we use ‘in case of’ with a noun (and not a verb, as per ‘in case’) and the noun is always a ‘problem’.

So it means “If there is this problem...(do this)”.

So commonly we use it as so:

• In case of a problem..
• In case of a fire…
• In case of an accident…
• In case of an alarm…
• etc

I hope that has been helpful, see you soon!

Adam Narbutt-Ryan

References & Bibliography

1. CAMBRIDGE GRAMMAR OF ENGLISH - Carter & McCarthy

2. Swan, Michael. Practical English Usage. Oxford University Press, Fourth Edition, 2016. Print. Specific sections: 69, 73, 76, 240, 244, 303

3. The Cambridge Grammar of the English Language – Huddleston & Pullam Specific sections: p107, p177,

Here are some links that could be of interest!

Check out: Conditionals: 14 Meanings of IF with SHOULD

Adam Narbutt-Ryan

Here to challenge.