Can a law enforcement officer be held liable for failing to protect a plaintiff from harm by failing to intervene too quickly?

As to the failure to protect claim, a law enforcement officer may only be held liable for failing to intercede if he or she had an opportunity to do so. See Cunningham v. Gates, 229 F.3d 1271, 1289-90 (9th Cir. 2000). If a constitutional violation occurs too quickly, there may no realistic opportunity to intercede to prevent the violation. See, e.g., Knapps v. City of Oakland, 647 F.Supp.2d 1129, 1159-60 (N.D. Cal. 2009). To establish a prison official's deliberate indifference in violation of the Eighth Amendment, plaintiffs must show that the official "knows of and disregards an excessive risk to inmate health or safety." Farmer v. Brennan, 511 U.S. 825, 837 (1994). "[T]he official must both be aware of facts from which the inference could be drawn that a substantial risk of serious harm exists, and he must also draw the inference." Id.