Interior Minister Eli Yishai's decision to arrest tens of thousands of asylum-seekers from Sudan in the near future is one of the gravest and most outrageous decisions the minister has ever made.

Yishai instructed his ministry's Population, Immigration and Border Authority to imprison all Sudanese migrants as of October 15, despite knowing full well that Israel cannot deport them. Their imprisonment, like their mass arrest, would be a gross violation of the international conventions Israel has signed.

When a minister's signature is affixed to such a gross violation, and he even announces his intentions publicly and proudly, Israel becomes a lawbreaking state - one that is deliberately ignoring the conventions it itself signed. It was not for nothing that a senior advisor to the UN High Commissioner for Refugees, Mickey Bavli, defined this move as "a crime that Israel has never before committed."

Yishai cannot be allowed to commit such a lawless act. The director general of the Prime Minister's Office recently spoke out vehemently on the issue, noting that "it's impossible to deport infiltrators from [Sudan and Eritrea] because their lives would be in danger there."

Now, the prime minister himself, along with the foreign minister, who is supposed to be aware of the significance of the conventions Israel has signed, must move immediately to thwart Yishai's plan. The government must announce at once that Israel will not do what its interior minister said it would, and that it respects the conventions it signed, as all law-abiding countries do.

Precisely now, when the southern border is gradually being closed and the flow of migrants into the country is steadily decreasing, Israel must find just and legal solutions for those migrants who are already here. It's no longer possible to intimidate people with warnings that "millions of Africans will flood the country." Now, it's necessary to allow those who are here, and who can't be deported, to live like human beings, in freedom.

Just as every country in the West has formulated an immigration policy that includes gradual paths to citizenship, Israel, too, must finally formulate such a policy for itself. Throwing tens of thousands of people into jail without trial, in violation of the law, for an unknown length of time would be a mark of Cain on Israel's brow.