The "numbers game" is today the most profitable of the wide-spread gambling rackets. And like all organized gambling it is a focal source and the financial support of far more serious crimes. At the same time it is one of the most difficult forms of crime for the police to control. It needs no costly installations which the police can confiscate or destroy. Unlike "house" gambling it cannot practically be harassed out of business. It can be operated by one man alone, if he survives failure to pay off for lack of capital; or by a syndicate with capital enough to hire runners. All that such operators need is some sort of headquarters to which pick-up men can report and where the bookkeeping can be carried on. This headquarters may be someone's private house, or merely a rented room. In consequence, the only possibility of holding such gambling in check is through discovery and punishment of its pick-up runners, or fortuitous convictions of the more important operators. And even this latter has been made almost impossible as a practical matter by judge-made limitations on police invasion of a criminal's privacy.
John B. Waite,
Search and Seizure - Suppression of Evidence - Judicial Attitude Toward Enforcement,
Mich. L. Rev.
Available at: https://repository.law.umich.edu/mlr/vol58/iss7/5