The use of an article
Here is the sentence:
In 2002, as defense minister, he had, according to French prosecutors in an ongoing case, taken a 114-million-euro bribe to buy French submarines.
May I ask why there is no article before the word defense? If I add the article the, how would the sentence's meaning change?
According to federal indictments, Goldman was drawn into the plot early in 2009, when two senior employees—Tim Leissner, head of investment banking for Southeast Asia, and Roger Ng, a managing director—first met Low.
Why isn't there an article - the - before federal indictments?
Blankfein told employees in a 2014 meeting, around the time federal prosecutors launched a criminal investigation of Vella’s dealings in Libya.
Similar for this, why isn't there an article before the word federal?
According to a 2019 federal indictment, Low sent Michel $21 million, much of it to be laundered into a number of Democratic campaigns.
Wheres for this sentence, there is an article (an) before federal.
Can someone explain?
The noun phrases in your examples are bare role NPs. These occur as the predicative complements of verbs like be, become, appoint, elect, as oblique predicative governed by as, and as complement of the preposition of following nouns like role, part or position. They are always replaceable by their counterparts with the because the interpretation is always definite. (CaGEL p409)
If you added the definite article in the first sentence, the meaning would be exactly the same.
In the second example given, federal indictments is indefinite and therefore does not need a definite article - the readers are not expected to be able to pick out specific indictments, and none are referenced in the article.
Also in the second example given, head of investment banking for Southeast Asia is an ascriptive supplement to NP anchor Tim Leissner. The relation between the two is comparable to that between a subject and predicative complement in a be clause (CaGEL p1357) which is why it allows a bare role NP. Here as well, the definite article could be added with no change in meaning.
Note that in the second example there is another ascriptive supplement a managing director to an NP anchor Roger Ng. In this case the indefinite article may not be omitted as that would change the interpretation to one where there is only one managing director.