"To threaten a lawsuit" means to warn someone that you will take legal action against them if they don't do what you want or stop doing something that you disagree with. Full definition
If a business does come under attack by a troll threatening a lawsuit over potential patent infringement, the business owner needs a less costly way to fight back. (inc.com)
One conservation group is taking credit for the action after threatening a lawsuit if such plans were not put in place. (wamc.org)
«More and more people are threatening lawsuits as a way to get money,» he says. (realtormag.realtor.org)