As per case facts, a petitioner was granted a mining lease and, upon executing the agreement, submitted it for registration and stamp duty assessment. The Collector determined a significant deficit ... in stamp duty and imposed a large penalty. The petitioner appealed, arguing that the stamp duty calculation was erroneous, as it incorrectly included dead rent and Upkar, and applied a higher stamp duty rate from a later amendment retrospectively instead of the lower rate applicable at the time of execution. The petitioner contended that only royalty should be considered for duty calculation. The question arose whether stamp duty on a mining lease should be calculated based on the law in force at the time of execution, and if dead rent or Upkar should be included in the calculation. Finally, the High Court ruled that stamp duty must be determined by the law prevailing on the date of execution. It found that the Collector wrongly included dead rent and Upkar in the calculation and erred by retrospectively applying a later amendment. Consequently, the penalty imposed was also deemed incorrect and set aside.