Criteria for comparing infrared spectra – A review of the forensic and analytical chemistry literature

•Literature review of the criteria used to compare IR spectra in forensic science.•Spectral library matching cannot individualize a sample.•Conclusions about the origin of the sample can be obtained based on class characteristics.•Similarity metrics do not separate chemical differences, only first order shape differences of the bands.•Instrument settings convolve and cannot be separated from chemical differences.