Final answer:
In the Illinois v. Gates case, an officer may be able to arrest an individual based on information from an anonymous informant if they can corroborate enough information. The 'totality of circumstances' test determines probable cause under the Fourth Amendment.
Step-by-step explanation:
According to the Illinois v. Gates case, an officer may be able to arrest an individual based on information from an anonymous informant if they are able to corroborate enough information. This case established the 'totality of circumstances' test to determine probable cause under the Fourth Amendment. The Court ruled that as long as the police can verify enough details from the informant's tip through their own investigation, they can make a lawful arrest.