a gate that can be opened or closed to control the flow of water on a river 防洪闸门;泄水闸门 - (figurative)
If the case is successful, it may open the floodgates to more damages claims against the industry (= start something that will be difficult to stop). 如果本案胜诉,就可能有更多的人向这个产业提出损害索赔,从而一发不可收拾。
- (figurative)