Is there deliberate gender preferential treatment in hiring or admission in STEM fields?

By "gender preferential treatment" I mean: Person A is selected ahead of Person B partly because of gender. In other words, Person B would have been selected ahead of Person A had gender not been taken into account.

By "deliberate" I mean: as a matter of policy at the department or university or state or national level, or at the discretion of the committee that makes the decision. This does not include unintentional bias, which might occur as part of human nature.

By "STEM fields" I mean: science, technology, engineering, and mathematics.

I'm interested in four stages.

1. 
   

   Graduate school admission

   
   


2. 
   

   Postdoc hiring

   
   


3. 
   

   Professor hiring

   
   


4. 
   

   Tenure or promotion decision

   
   

Answers can be about any country. But please keep in mind that the question is not about why deliberate gender preferential treatment is a good or a bad idea. It is about what happens in reality.

Answers should be supported by either references to publicly available policies, research, or firsthand personal experience (e.g. on hiring committees).