Noun can be used as countable and Uncountable
Decision
Your decision is not correct (Uncountable)
Give a decision to the issue (countable)
Decision
Your decision is not correct (Uncountable)
Give a decision to the issue (countable)
Justice
Socrates was not given a fair justice (countable)
Hazrat Omar was an embodiment of Justice (Uncountable)
Most uncountable nouns can be countable in certain situation.
But in both your examples 'decision' is countable and it can never be uncountable.
