What characterizes passive bloodstains?

Passive bloodstains are characterized by their behavior under the influence of gravity. This type of bloodstain occurs when blood falls or drips onto a surface without any additional force being applied to it. The shape and patterns of passive drops depend largely on the surface they land on and the distance they fall, which further emphasizes their passive nature.

They typically form when blood is simply dripping from a wound or any object, as opposed to being projected or splattered by a forceful impact. The key quality of passive bloodstains is that they rely on gravity to create their patterns, which distinguishes them from other types of bloodstains that are formed through active means, such as impact or force. Understanding this characteristic is crucial for forensic analysis, as it helps in determining the nature of the incident related to the blood evidence.