Update - The General Assembly voted to overrider the veto. See this helpful link on Maryland's sick leave law.
On May 25, 2017, Governor Hogan vetoed the "Maryland Healthy Working Families Act." This Act would have mandated that private-sector employers who employ more than 15 employees provide paid sick leave. Employees would have earned 1 hour of paid sick leave for every 30 hours that they worked. But, as noted, Governor Hogan vetoed the Act.
Had the bill not been vetoed, it would have preempted the one Maryland jurisdiction that has a paid sick leave law. That is Montgomery County, which has passed the Earned Sick and Safe Leave Law.
Governor Hogan claims to support a version of paid sick leave, but would limit it to employers with more than 50 employees and would offset the costs through tax incentives. Governor Hogan established a "Committee on Paid Leave" to study how best to implement paid leave.
Maryland's leave laws are summarized in this chart.