INCOSE's first and primary certification level, Certified Systems Engineering Professional (CSEP), is the right fit for most systems engineers. Those who can work independently to tailor and implement systems engineering activities are probably qualified to be CSEPs. 

How do we check that probably? We have a team of dozens of volunteer reviewers. They look through individuals' reports on their systems engineering activities and they compare those to what the references state. This thorough review is unlike what some other certification programs do. We have human eyes on every application package. This takes some time, both to perform that review and because of the logistics of assigning reviews and filling in gaps, but it's worth it. INCOSE CSEPs are reliably good.