In Shri Gurbaksh Singh Sibbia vs State of Punjab (1980) 2 SCC 565, the Constitution Bench of the Supreme Court, while upholding the constitutionality of Section 438 Cr.P.C., observed thus:
Thirdly, the filing of a First Information Report is not a condition precedent to the exercise of the power under Section 438. The imminence of a likely arrest founded on a reasonable belief can be shown to exist even if an F.I.R. is not yet filed.
Another Constitution Bench in Sushila Aggarwal vs State (NCT of Delhi) also observed thus:
An application for “anticipatory bail” in anticipation of arrest could be moved by the accused at a stage before an FIR is filed or at a stage when FIR is registered but the charge sheet has not been filed and the investigation is in progress or at a stage after the investigation is concluded.
So the issue is well settled by at least two Constitution Bench judgments and therefore it is not necessary to quote other caselaws.