Cannabidiol, Morphine, Pain

Inclusion Criteria: * Participants must report having smoked a cigarette (nicotine or marijuana) AND having taken an opioid on 3 or more occasions in their lifetime. * Participants must be in good health to participate; those with certain contraindications will be excluded. * All participants will undergo psychiatric evaluation and will be asked to report their substance use history by interview and structured questionnaire methods. * Participants will undergo medical evaluations using medical history, physical exam, standard lab tests (complete blood chemistry, urinalysis, urine pregnancy test for females), and 12-lead ECG. Exclusion Criteria: * Serious psychiatric illness (e.g. psychotic or bipolar disorder, recent suicide attempts; severe depression) * Substance Use Disorders other than Nicotine Use Disorder and Mild Cannabis Use Disorder * Neurological diseases; cardiovascular problems (e.g. systolic BP \>140 or \<95 mmHg, diastolic BP \>90 mmHg, abnormal ECG); pulmonary diseases; systemic diseases (e.g. liver, renal, inflammatory) * Cognitive impairment (\<80 IQ) * Past-month medications that increase study risk * Women who are pregnant (urine HCG), lactating (self-report), or if heterosexually active and not using (self-report) medically approved birth control (oral or depot contraception, IUD, condom/foam, sterilization, tubal ligation) * Individuals unable to give informed consent will be excluded.