In the letter, Article 19, Human Rights Watch, and International PEN express their "profound concern" about the prosecution of youth activists Emin Milli and Adnan Hajizada, whose trial began on Friday in Baku.
Milli and Hajizada are charged with disorderly conduct and inflicting bodily harm in an altercation in a Baku restaurant on July 8.
In the letter, the groups remind Aliyev of "Azerbaijan’s international commitments to ensure the protection of the right to freedom of expression and the right to a fair and public trial by an independent and impartial tribunal."
It notes the apparent targeting of Milli and Hajizada, the failure of police to take their assault complaint seriously; the refusal to provide the two men with adequate medical care; the refusal to allow them access to a lawyer; and the decision to place them in two months' pretrial detention, "which appears unnecessarily harsh given the nature of the alleged crime of 'hooliganism.' "
It adds the "prosecution of Milli and Hajizada, who used online blogging to further their civic participation, is particularly troubling in light of deteriorating media freedoms in the country."
Read the letter in full here.