Despite popular perception, polygraph tests do not detect lies. Instead, they measure physiological responses—such as heart rate and breathing—correlated with stress. Scientific evidence consistently demonstrates the unreliability of polygraphs in accurately identifying deception. This unreliability has led to increasing scrutiny of their use in legal contexts. Costa Rican jurisprudence, specifically, is questioning the validity and legality of admitting polygraph results as evidence. Experts emphasize the tests measure arousal, not necessarily dishonesty, making results susceptible to manipulation and misinterpretation. The findings raise concerns about the potential for wrongful accusations and convictions based on flawed technology.