George Clooney -- Italian Wedding Legal and Binding

George Clooney didn't do what some celebs do when they tie the knot overseas ... in his case, marriage on foreign soil is legal and binding, because we have the official document that says so.

We've seen it before ... a celeb gets "hitched" outside the U.S. but it's all window dressing. The couple quietly comes back to our country and legally ties the knot.

Check out the certificate, issued by the City of Venice, Italy. It certifies that George Timothy Clooney and Amal Alamuddin have a legally binding marriage contract.