Genitive Case with "s"

Question

In most lessons about the German genitive case I was instructed to use the articles (and similar endings for adjectives) "des" for masculine and neuter and "der" for feminine and plural. However I did see some scripts and even heard in movies where they use the English style where you would say "Max's car" or "Carrie's table". In one example there is a scene in "Inglorious Basterds" where the drunk officer annoys Michael Fassbender's character, and to me it sounded like he said

Das ist ein Offiziers tisch.

I could be wrong but is there some colloquial rule for the genitive case in German?

Answer 1

What you heard in inglorious bastards was not a genitive case, it was a compound noun:

Das ist ein Offizierstisch.

There is a loose relationship between genitive case and some compound nouns, but compound nouns are a separate topic. There are hundreds of questions about compound nouns here on German Stackexchange.

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Now about genitive case.
There are more than one ways to build the genitive case in German.

In English you can say:

1. This is my father's car.
2. This is the car of my father.

In German you can say:

1. Das ist meines Vaters Auto.
2. Das ist das Auto von meinem Vater.
3. Das ist das Auto meines Vaters.

In English, in #1 "my father's" is a prepositive (i.e. prepended) genitive attribute of the noun "car". Same for the German #1: "meines Vaters" also is a prepositive genitive attribute of a noun (of "Auto").

In #2 we have in both languages a postpositive prepositional attribute ("of my father" and "von meinem Vater") of the same noun. There is no genitive case in these sentences.

The Version #3 does not exist in English, only in German (and maybe in other languages). The part "meines Vaters" is a postpositive genitive attribute. If English had this feature, you would get this sentence:

(hypothetical:) This is the car my father's.

Note, that since we have a postpositive attribute, i.e. an attribute that is placed after the noun, we need an article before the noun.

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The prepositive genitive attribute was used in the past more frequent than in modern German. One of its names is "sächsischer Genitiv" (Saxon genitive), where "sächsisch" stands for angelsächsisch (Anglo-Saxon), and this name in fact refers to its usage in English (i.e. Anglo-Saxon) language.

You find this kind of Genitive in modern German still very often when the attribute is a name:

Das ist Walters Auto.
This is Walter's car.

But there are also some idiomatic phrases that use this Saxon genitive:

Das ist des Rätsels Lösung.
This is the riddle's solution.

And, as said before, in old and poetic texts:

Des Kaisers neue Kleider
The emperor's new clothes

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But the preferred genitive attribute in german is the postpositive:

Im Museum sind die Kleider des Kaisers ausgestellt.
Ich fand die Lösung des Rätsels ganz ohne fremde Hilfe.

But not for names:

(wrong:) In der Garage steht das Auto des Walters.
(correct:) In der Garage steht Walters Auto.

But (not a name):

(correct:) In der Garage steht das Auto des Vaters.
(correct:) In der Garage steht Vaters Auto.

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Also note, that the usage as an attribute for genitive case is an exception. You can't use any other case to build attributes (i.e. there is no dative attribute or accusative attribute in German).

The usual way to use grammatical cases are objects. Note, that there are no direct in indirect objects in German! German has dative objects, accusative objects and genitive objects (and prepositional objects which are a topic on its own).

Genitive objects often are hard to translate, because they do not exist in English, and so you have to find a different construction that is able to express the same or at least a similar meaning.

Genitive objects:

• Wir gedenken der Toten.
  We commemorate the dead.

• Deine Frisur spottet jeder Beschreibung.
  Your haircut defies any description. (Your haircut beggars belief.)

• Ich erfreue mich bester Gesundheit.
  I enjoy best health. (I am in perfect health.)

Not only some verbs, but also some adjectives need genitive objects:

• Ich bin des Deutschen mächtig.
  I am able to speak and understand German. (literal something like: I am powerful of German )

• Die Ermittler wurden der Täter habhaft.
  The investigators caught/secured the offenders. The investigators got hold of the offenders. (literal: The investigators became have-able of the offenders)

• Er handelt bar jeglicher Vernunft.
  He acts irrational. (He acts lacking any rationality.)

Also some prepositions need genitive objects:

• Abzüglich der Steuern ergibt das 800 Euro.
  Less taxes, this gives 800 euros.

• Italien liegt südlich der Alpen.
  Italy is located south of the Alps. (literal: Italy lies southly of the alps)