More than half the states of the nation have made it a crime to make a child abuse report one knows or believes to be false. Descriptions of these laws have been gathered here. All the states of the Pacific Northwest have such laws.
The laws of six states—California, Colorado, Idaho, Indiana, Minnesota, and North Dakota—also specify that the reporter may be liable for any damages caused by the false report. (In other states, more general laws may also impose such liability.)
Prof. Daniel Pollack of Yeshiva University has written about the criminal laws here.