This dissertation studies how criminal law affects decision-making and behaviour in the world's second largest jurisdiction, Russia. The information on judicial decision-making comes from a novel data set on the universe criminal defendants processed in the country in 2009–2013. First chapter asks whether pleading guilty to a crime leads to a reduction in sentence length. Results reveal high heterogeneity of individual benefits to pleading guilty and that pleading is most rewarding for those who choose not to plead guilty. Second chapter examines whether repeat offenders commit more serious crimes at the later stages of their criminal career. I find pronounced escalation in offence severity in the country which is robust to modelling assumptions and is observed in other jurisdictions. Third chapter uncovers a discontinuity in punishment for drug crimes in Russia. I employ a regression discontinuity design to find that length of unconditional real incarceration increases by 0.84 years when the drug weight crosses the significant-large weight threshold. The observed discontinuity is extraneous to the law but is strongly manifested in practice, highlighting the expressive function of the said law.