Necessity of MoU for researcher exchange or collaboration In my research institute, there is a fair amount of discussion around wanting to collaborate or create exchanges with other labs, especially outside of the country (we are in Asia).  From myself and a few other researchers, we have connections to labs in the US from graduate school and previous research. 

On my own initiative, I exchanged interns and research assistants between my lab and one in the states.  It was specific on the people we had, such that a student interning in my lab would benefit from going to the lab in the states and vice versa, as we worked on a common project. 

The higher-ups want to make some "official" exchange, which may be some asian culture at play.  From this, the conversations are always around signing a memorandum of understanding (MoU).  For the exchange I worked on, we had specific people and specific goal, so a general Lab to Lab MoU did not seem as relevant as a mutual agreement of what the purpose of the exchange was.

My question is, how important or useful is an MoU, are there pros and cons to this?  I don't think it has any legal weight, so does anyone have experience with this type of collaboration and see why it is necessary in an overall scale?  Is signing an MoU the only way for an institute to call an exchange 'official'?
MOUs serve several purposes in my experience. First, they put down in writing what the two labs have agreed to do together. This formalizes the relationship a little and allows the participants to refer back to their commitments. Sometimes people get busy and forget to do some parts of the agreement. The MOU allows the other side to gently remind their partners that everyone committed to something and ask them when they will start on their part. People don't generally intend to shirk their responsibilities, but academics and researchers get busy, so informal and unpaid promises are first to slip. MOUs which formalize the relationship are often enough to make sure each side holds up its end.

Second, they allow others inside and outside the respective organizations to recognize that the relationship exists. Labs have directors, their directors have bosses (often department chairs, deans, or research vice presidents), and their bosses have bosses on up the chain. Having an MOU between labs establishes a formal relationship that can be recognized by these people. In fact, depending on the organization, the boss of the lab director may have to sign off on the MOU (not just the lab director themselves), which gives the agreement some level of officialness.  

This official recognition generally doesn't get used for much more than promotion of the relationship between the labs. Though, it may also serve as the first step in a deepening relationship between larger parts of the overall organizations (departments, colleges/schools, and even whole universities or government entities). These formal relationships can also be helpful in pursuing government funding in some countries to help support the collaboration. 

I've never used an MOU to formalize a simple summer student exchange. Those, in my experience, were always done with a verbal or email agreement. However, everything longer than a summer or more complicated than a student exchange that I've been involved in has had a written MOU. They lay out the expectations and give the signers cover with their higher-ups when the questions come about what two groups are doing together. 

It's not generally seen as a contract, but does up the seriousness of the relationship to have an MOU.