These provide evidence that women were definitely fighting immediately before each law was passed, and probably in reasonably large numbers, otherwise there'd be no need for the law. Also, the fact that a law exists doesn't mean that it is universally obeyed, or that those disobeying it would be social outcasts. (consider: traffic laws such as speed limits and parking restrictions, dog licencing in the UK, pirate videos and computer software, and so on)
Emperor Alexander Severus issued an edict prohibiting women combatants in the arena in 200 AD
Women were barred from military participation in a law passed at the synod of Druim Ceat in 590 A.D. The law proved to be unenforceable when the women warriors refused to lay down their arms.
Papal Bull of 1189 prohibited women from joining the Third Crusade
In 1644 King Charles issued a proclamation banning women who were with the armies during the English Civil War from wearing men's clothing.
In 1795 the French revolutionary government ordered Frenchwomen to return to their homes and prohibited them from attending political meetings, or gathering in groups of more than five.
Women were ordered out of the front lines of the Israeli Army by David Ben Gurion in 1950 (the last one left in the mid 1960s)