Session types provide a means to prescribe the communication behavior between concurrent message-passing processes. However, in a distributed setting, some processes may be written in languages that do not support static typing of sessions or may be compromised by a malicious intruder, violating invariants of the session types. In such a setting, dynamically monitoring communication between processes becomes a necessity for identifying undesirable actions. In this talk, we discuss how to dynamically monitor communication to enforce adherence to session types in a higher-order setting. We present a system of blame assignment in the case when the monitor detects an undesirable action and an alarm is raised. We will also discuss ongoing research about improving the precision of the blame assignment.