To be unconstitutional Israel should first have a constitution. The Declaration of Independence is NOT a constitution. Laws that contradict it can be and have been passed. Israel doesn't want a constitution for it would require to declare explicitly its racist nature, or ditch once and for all the double standards that discriminate against the Arab natives. Ambiguity is always preferred by Israel.
Russia is not and will not launch infantry operations in Syria, says senior lawmaker (Reuters)
from the article: ANALYSIS / Lieberman's loyalty oath isn't unconstitutional, it's unwise