Diplomatic immunity in case of sexual harassment

Question

Whether diplomatic immunity is considered as a privilege or a right, I am not sure but is there any law by which we can prosecute an individual with diplomatic immunity especially in cases involving sexual harassment. Since the laws defining the nature of harassment are different in east, west and middle east nations, how are these cases resolved assuming that both the states where the case has occurred and that to which the diplomat belongs are not permanent members of Security Council of UN nor any of them have nuclear capability. They also do not share any part of their respective state boundaries.

Answer 1

Diplomatic immunity is a privilege granted by the host or receiving country to an ambassador of another nation recognized diplomatic agents and their families. It exists under the 1961 Vienna Convention on Diplomatic Relations, so there is a set of rules everyone has to play by. The idea is so that host countries do not legally harass people who are representing their country within that nation.

Typically Diplomatic immunity comes up most often in traffic enforcement, as cars with Diplomatic plates tend to violate traffic and parking laws regularly. That said, the police of the host nation are allowed to ticket the offender. However, there's little they can do to enforce the fines against the ambassador after the ticket is written. That said, most police will still write them as some nation's foreign services offices do actually make the diplomats pay the tickets (in fact, an unofficial barometer of corruption in a nation's government is how likely diplomats are to pay their tickets.).

That said, committing a serious crime while under diplomatic immunity is a major international incident. The receiving country will perceive the crime as an endorsement of the sending nation. The most immediate remedy is the sending nation waives Diplomatic immunity, at which point the receiving nation can prosecute.

There are times where this doesn't happen (often the sending nation and recieving nation punish the crime differently) at which point one of three things will happen. Either the sending nation will recall the diplomat (effectively removing them from their job) and punish them based on their own laws, if any exist.

If that is not done, the receiving nation can declare the diplomat as Persona non Grata (lit. Unwelcomed Person) which is effectively a person specific ban on entry into the country (the sending nation can send whoever they want to be a diplomat... but that specific person cannot enter the receiving country.). As such, the diplomat who is named PNG is given some amount of time to leave the receiving country or have their diplomatic immunity revoked. It's the international equivalent of "You don't have to go home, but you can't stay here."

If neither of those work, than the receiving nation can cut off diplomatic ties, and in some cases has a good cause for war over the matter (A diplomat who Murders the citizen of a host nation and isn't recalled or has their immunity waived has just committed an assassination's sanctioned by the sending nation, which is a justification for war.).

Answer 2

Is there any law by which we can prosecute an individual with diplomatic immunity

With the consent of the sending country, certainly.

Without such consent, no.

Diplomatic immunity is a little complicated in that some people (e.g. ambassadors) have total immunity, others (technical and administrative staff) only have immunity for acts in the course of their duties (see https://law.stackexchange.com/a/21436).

It is possible that sexual harassment could be ruled to not be "in the course of their duties".