Can a landlord come in to your rental property and unlock the lock onyour bedroom door?

A landlord's right to enter their rental property can be, and is, a source of conflict with tenants.  Many landlords may believe that because they own a property, that they have a right to enter it ant time they please.  On the other hand, a tenant may believe that they have no obligation to permit a landlord to enter the property or that they have no choice but to tolerate a landlord's invasion of their privacy. Many states and localities have laws that define a landlord's "right of entry" into a rental unit.

In MI, a landlord who enters without permission or notice is trespassing.  State law says tenants are entitled to privacy.  A landlord must give "reasonable notice" before entering (typically 24 hours or more).  Basically, if it is not an emergency or your lease specifically states otherwise, your landlord cannot legally enter your rental without permission or notice.  Potential remedies include calling the police at the time the illegal entry occurs and withholding rent the next time it is due.  Consult directly with a real estate attorney as to this. You may even be able to negotiate compensation for the privacy invasions.  That having been said, a landlord can enter the property unannounced if such entry is necessary to cure a dangerous condition, prevent destruction, or to respond to a bona fide emergency on the premises. There is, however, no legal requirement that a landlord notify a tenant prior to making entry under such circumstances. 

Note:  Sometimes tenants feel that the only solution is to add or change locks. You could add a second lock and leave it unlocked when your landlord has requested access but you are unable to be there to let her/him in.  But if there is an emergency, your landlord may need to enter your unit.  If your landlord or emergency personnel need to break down the door to get in, you may be liable for the cost of repairing or replacing the door.