Zhovtis, the director of the Kazakh nongovernmental organization Bureau on Human Rights, was sentenced last week to four years in jail for his alleged role in a fatal traffic accident.
Zhovtis calls the verdict a "political outrage."
The United States, the Organization for Security and Cooperation in Europe (OSCE), and Human Rights Watch (HRW) have called for the Kazakh authorities to revise or void Zhovtis's sentence, which they consider unfair.
They also believe the charges against Zhovtis are politically motivated.
Zhovtis is known as the leading human rights advocate in Kazakhstan and has often been critical of Kazakh authorities.