Simple Past or Past Perfect

Question

If I went to a place last night where I needed to show an id, but I forgot to have it on me. So if in the morning I was speaking to a friend(reporting on what happened), which one of the following would be correct:

I had heard that you needed an ID, but I didn't know if it was absolutely necessary

I had heard that you need an ID, but I didn't know if it was absolutely necessary.

I heard that you need an ID, but I didn't know if it was absolutely necessary.

The first one seems correct to me, but I might be wrong. Ideas?

And which one of the following should I say in the context above:

Reporting on what had happened

Reporting on what has happened

Reporting on what happened

Answer 1

I had heard that you needed an ID, but I didn't know if it was absolutely necessary.

This sentence is correct. It implies that you knew about the necessity of carrying an ID before the events of last night.

I had heard that you need an ID, but I didn't know if it was absolutely necessary.

This is also correct, although some people might say that the use of Present Simple with need doesn't agree with the past perspective. I believe, however, you can use it because in this place the ID is a norm and it is still valid.

I heard that you need an ID, but I didn't know if it was absolutely necessary.

This is correct but not very clear. I heard doesn't show that you knew about the ID beforehand. I prefer the previous two examples.

You are reporting what happened since you have already mentioned that these events took place last night.

Answer 2

If you're talking right now about a past event which happened once and you exactly specify when (all this would be your case right now), you are:

Reporting on what happened (last night).

By saying:

(Last night) I heard that you need an ID, but I didn't know if it was absolutely necessary.

The last night parts are there to specify that you're talking about a past event which happened once. You can omit those parts if they're already implied in the text from what you've said before. In your case they are, but I put them to emphasize the fact that they need to be expressed one way or another.

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Case 2: When would you say "what had happened?"

You'd use this tense if you were going even further to the past, before a certain event already in the past, like this:

When John entered the room he complained that the towels had been stolen.

As you can see in this example, the first point in the past is "John entering the room" and the second point in the past, which happened before the first point, is "the towels having been stolen."