Hello! I'm currently a third year student at Moscow State University law school(best in Russia according to QS). I would like to know whether participating in summer law school programs will have positive effect on my chances to get later admitted to LLM programs at US law schools?
(Columbia/PennLaw)
My area of interest is corporate/business law. I'm currently thinking about participating in Summer U.S. Business Law 2018 Program a at PennLaw.

Because there's no assessment, I don't think that will have any notable effect. I guess it does at least show that you can get into the country.

A for-credit school will be better. Here is Cornell's summer law school, in Paris. http://www.lawschool.cornell.edu/international/study_abroad/paris_summer/program.cfm#CP_JUMP_35934