From Longman Dictionary of Contemporary Englishhem somebody/something ↔ in phrasal verb1 AROUND/ROUNDto surround someone or something closely They were hemmed in on all sides by the soldiers and the dogs. The market place is hemmed in by shops and banks.2 FREE TO DO WHAT YOU WANTCAN'Tto make someone feel that they are not free to do what they want to do They hem in the child with endless rules and restrictions. → hem→ See Verb table
Examples from the Corpus
hem in• A second group of police assembled behind the marchers, effectively hemming them in.• It's made from 100% easy-care polyester and measures 24in from nape of neck to hem.• Silently, ranks of police edged their steaming mounts closer to the crowds, hemming them in.• Some crew slide on to the seat beside me, hemming me in.• They became an accounting device to help managers, not a control device to hem them in.• You hem me in, behind and before; you have laid your hand upon me.• Six black heavies hem us in, want to know why we are snooping. 