According to the 21 CFR 211.113 (b) ‘Appropriate written procedures, designed to prevent microbiological contamination of drug products purporting to be sterile, shall be established and followed.
Such procedures shall include validation of any sterilisation process’, it has clearly drawn a focus on the importance of sterilizing filtration system to be properly designed across all the bio-tech manufacturing processes.
http://learnaboutgmp.com/considerations-sterile-filtration-validation-21-cfr-211-113-b/