Israel's Supreme Court has upheld a law banning Palestinians who marry Israelis from gaining Israeli citizenship.
Civil rights groups had petitioned the court to overturn the law, saying it was unconstitutional.
"Human rights do not prescribe national suicide," Judge Asher Grunis wrote in the judgement.
The law was introduced in 2003, with its backers citing security concerns and the need to ensure Israel remains a Jewish-majority state.
Human rights activists and Arab politicians condemned the court's decision.
The court "had failed the test of justice", said Arab-Israeli MP Jamal Zahalka of the Balad party.
"It is a dark day for the protection of human rights and for the Israeli High Court," lawyers from the Association for Civil Rights in Israel told AFP.
"The ruling proves how much the situation regarding the civil rights of the Arab minority in Israel is declining into a highly dangerous and unprecedented situation", Arab-Israeli civil rights group Adalah, one of those that brought the petition, said in a statement.
The Citizenship and Entry Law was passed in 2003, during the second Palestinian intifada (uprising), as waves of suicide bombings targeted Israel.
Many were launched from the West Bank, some with the help of Israeli Arabs.
Initially, the law was emergency legislation which has since been extended periodically.
It was amended in 2005, allowing women over 25 and men over 35 to apply for temporary permits to live in Israel, but still ruling out citizenship for all but a handful of cases.
In 2007, it was expanded to apply to citizens of Iran, Iraq, Syria and Lebanon.