Article 548 was abolished by Bashar al-Assad's presidential decree
Syria has scrapped a law limiting the length of sentences handed down to men convicted of killing female relatives they suspect of having illicit sex.
Women's groups had long demanded that Article 548 be scrapped, arguing it decriminalised "honour" killings.
Activists say some 200 women are killed each year in honour cases by men who expect lenient treatment under the law.
The new law replaces the existing maximum sentence of one year in jail with a minimum jail term of two years.
Justice Minister Ahmad Hamoud Younis said the change was made by the decree of President Bashar al-Assad, following a recent increase in "wife-killings... on the pretext of adultery".
The new law says a man can still benefit from extenuating circumstances in crimes of passion or honour "provided he serves a prison term of no less than two years in the case of killing".
The legislation covers any man who "unintentionally" kills his wife, sister, daughter or mother after catching her committing adultery or having unlawful sex. It also covers cases where the woman's lover is killed.
Reports say women's rights activists have given a cautious welcome to the change, with one group calling it a "small contribution to solving the problem".
Their objection remains, however, that the new law still apparently invites men to murder women if they catch them having sex or suspect them of doing so.