Is using L1 when teaching L2 okay?

Something that wonders most teachers if not all. Can we use our native or first language in our classrooms when we are teaching a second language? Can we use it when we need to?
Of course many research has been done to show whether it is okay to use it or not. 
Some research claims that we should not use any of our first language, and the student must be able to learn the language autonomously without the aid of their second language. Moreover, this teaches them to think in the second language, which makes it more authentic.On other hand other research which is recent claims, that it is actually better to add some of our L1 usage in teaching, of course the higher the level the less usage is needed, in addition students should be aware of when they can use it and how much. 
Also, research has claimed that why hinder the fact that we have a lot of knowledge in our L1 that can be helpful and essential to the learning process of the students and not use it. 

In an Educational Philosophy course, my self and my peers under the supervision of our professor did a small debate of who is with and against using L1 in teaching a second language. The purpose also, was to show the pros and cons of both points of view, supported with evidence and research. 

Even though we had a lot of evidence that showed the importance of using L1 in situations where we can make it easier for the students to grasp meanings and terms, however the other team won according to personal experiences they were able to prove that not using it was better.

Personally, I am with using it. Of course with limits, but when we need to use it, we can. It is not a crime! In some cases it might make things easier for both the teacher and the students.