Have teeth
Definition 1 of 2
Pro Tip 1/3Enforcement Power
Refers to a law or rule's ability to be imposed effectively. 
The environmental law has teeth due to the heavy fines for non-compliance.
Pro Tip 2/3Serious Consequences
Indicates that there will be significant penalties if the rule is broken. 
Beware, the company's new policy has teeth—violators will be suspended immediately.
Pro Tip 3/3Implying Urgency
Suggests the matter is important and requires immediate attention. 
The boss said the guidelines have teeth and must be applied at once.