Direct Evidence and Circumstantial Paths
Direct evidence is testimony or a document that directly proves a fact without inference: an eyewitness saying 'I saw the defendant stab the victim' is direct. Circumstantial evidence requires the jury to draw a logical inference: a defendant's DNA found at a crime scene is circumstantial (it does not directly prove they committed the crime, though it strongly suggests presence). Both are admissible and often equally probative. Juries are instructed that they can convict on circumstantial evidence alone; the difference is inferential distance, not legal weight. Expert testimony (fingerprint analysis, DNA, psychiatric evaluation) is a distinct category, admissible if the expert is qualified and the methodology is reliable under Daubert or similar standards.
Hearsay, Character, and Strategic Exclusions
Hearsay (a statement made out of court offered to prove its truth) is generally excluded unless an exception applies: excited utterances, dying declarations, statements against interest, prior consistent statements, and many others. Character evidence is mostly barred: you cannot introduce evidence that the defendant is a violent person to suggest they committed a violent crime, though the defendant can open the door by claiming good character. Privileges shield certain communications: attorney-client, doctor-patient, spousal, clergy-penitent. These rules exclude probative but unreliable evidence and protect relationships the law values more than fact-finding.