STORY: Israel on Monday (March 30) passed a new law making the death penalty the default punishment for Palestinians convicted of lethal attacks.

The law mandates execution by hanging for attacks deemed to be, quote, "negating Israel's existence."

But while it would also apply to Israeli citizens, critics say using that definition it makes it highly unlikely the measure would ever be used against Jewish Israelis.

In the West Bank city of Ramallah, families of Palestinian prisoners gathered in protest, saying the law has left them fearing for their loved ones' lives.

"My son carried out an operation, and this decision might be applied to him and it might not, but I fear for my son's life. Last night we did not sleep. As a mother of a prisoner, and like all other mothers of prisoners, I am sure none of them have slept since the news came out. Our sons have been in there for three years now, subjected to hunger, thirst, cold and illnesses."

Law professor Mordechai Kremnitzer from the Israel Democracy Institute says the Supreme Court could ultimately strike down the law:

"The likelihood of executions in the near future is not very high. I think Israeli judges will show a negative attitude towards capital punishment because it runs against both universal morality and Jewish morality."

"The main problem of this law is that it makes a difference between the same type of terrorist killers on the basis of ethnic origin. And this is against any principle of equality before the law."

"It's a clear case that invites the Supreme Court to strike it down."

International criticism has been swift to come. 

The outgoing boss of the UN agency for Palestinian refugees, Philippe Lazzarini, called the move discriminatory: 

"I have been absolutely appalled by this abject law, which I really hope will be rejected by the Supreme Court. I think I'm not aware of democratic countries reinstating the death penalty. And on top of that, this would be an extraordinarily discriminatory law, because it would basically target only one category of the population."

European Union spokesperson Anouar El Anouni also criticized the move:

"The death penalty bill in Israel is very concerning to us in the EU. This is a clear step backwards, the introduction of the death penalty, together with the discriminatory nature of the law."

The Palestinian Authority's minister for prisoners estimates that 45 to 47 Palestinian detainees are awaiting sentencing on murder charges and could face the death penalty if the law is implemented.