The phrase "justification for retaining" is correct and usable in written English.
It refers to the reasons or rationale for keeping or holding onto something. Example: The company presented a detailed report outlining the justification for retaining their current CEO. They cited his strong leadership skills and successful track record as the main reasons for their decision.
As a justification for retaining her two aides, Ms. Hanover's lawyers filed an attachment listing some duties of the staff.
The Met says the domestic extremism unit deleted many files recently after a watchdog found there was no justification for retaining them.
Richard Allan, the Liberal Democrat MP leading the Parthenon 2004 campaign for their return in time for the Athens Olympics, said the museum had lost all justification for retaining the sculptures, which were torn from the Acropolis by Lord Elgin in 1802.
However, such numerical convergence between the results of two different operations was regarded by Bridgman as merely a "practical justification for retaining the same name" for what the two operations measured (Bridgman 1927, 16).
In measurement terms there was little justification for retaining six measures when one would suffice.
If this contention cannot be supported, then the justification for retaining open-ended items in summative assessment may be questioned.
But on Thursday, harbor officials barred a French boat from refueling, he said, an indication that Greek officials might find justifications for retaining the other ships in port.
The only justification advanced by the police for retaining the photographs for more than a few days after the meeting was the possibility that the appellant might attend and commit an offence … that justification does not bear scrutiny".
This has provided the justification for Hizbullah's claim to be retaining its arms for the purpose of liberating Lebanese territory from Israeli occupation.
His justification for these shifts is that if he can retain the support of moderate Eurosceptics – so that no more than, say, 50 Tory MPs back "Brexit" – he is more likely to win the referendum.
That privately run charter schools cannot attract and retain certified teachers "is hardly a justification for lowering the quality standards for teachers".
