Twitter CEO Jack Dorsey has made it a top priority for company to limit hateful conduct. In late December 2015, for example, the company changed its rules to explicitly ban "hateful conduct " for the first time. A new report says Twitter is working to further curb the rise of hateful conduct as it is " working on a keyword-based tool that will let people filter the posts they see , giving users a more effective way to block out harassing and offensive tweets." Bloomberg reports: