Questions & Answers about Ισχύει αυστηρή ποινή.
ισχύει comes from ισχύω, which often means to be in force, to apply, to be valid, or to hold.
In this sentence, it does not mean physical strength. It is being used in the legal/regulatory sense: a strict penalty is in effect or applies.
So Ισχύει αυστηρή ποινή has the feeling of:
- A strict penalty applies
- A severe penalty is in force
- There is a strict penalty in effect
This is a very natural kind of wording in formal notices, rules, and regulations.
Because ποινή is the grammatical subject of the sentence.
The verb ισχύει is third person singular, and ποινή is a singular noun, so they match:
- ισχύει = it applies / is in force
- ποινή = penalty
In English, we might feel that the sentence is close to there is a strict penalty, but in Greek the structure is more like a strict penalty applies. That makes ποινή the subject, so nominative is correct.