As to the validity of the heavily regulated industry inspection, the Court found that the doctrine is not applicable to traveling on a state highway.

The officers stopped Almeida-Sanchez on California Highway 78 at a point twenty-five air miles north of the Mexican border.

The United States argued that the Immigration and Nationality Act Section 287(a)(3) authorizes warrantless searches of vehicles within a reasonable distance of the land border.

In Carroll v. United States, the Court permitted a warrantless search of a vehicle because officers risked losing evidence if the car left their jurisdiction while they try to secure a warrant.

In this case, the United States conceded that the Border Patrol officers did not have probable cause to stop Almeida-Sanchez or to search his vehicle.

The officials who stopped Almeida-Sanchez exercised “unfettered discretion.” The Court found that the officers' discretion was not sufficiently circumscribed by an area warrant to be a constitutionally permissible administrative search.

In Colonnade Catering Corp. v. United States, the Court upheld warrantless inspections of a company for its liquor sales and manufacturing.

Entering into these industries entails knowledge that business records will be subject to inspection, which limits the owner's justifiable expectation of privacy.

The Court further noted that in Colonnade and Biswell inspectors also had specific knowledge that the businesses did actually sell liquor and guns, respectively.

[13] After finding that no warrant exceptions applied here, the Court considered validity of Section 287(a)(3) of the Immigration and Nationality Act[14] and its associated regulations authorizing warrantless searches of vehicles within 100 miles of the land border.

[15] The Court did not declare the provision unconstitutional, but adopted an interpretation of the statute that would not authorize warrantless stops and searches like the one in Almeida-Sanchez's case.

Incident to this power, Congress may require searches of each individual seeking entry into the United States, as well as her vehicle.

[18] Justice Powell also explains the government interest in having roving patrols: many individuals enter the United States unlawfully, avoiding designated points of entry, and meet with someone who will transport them in a vehicle.

[19] Justice Powell discusses the administrative search exception to a particularized warrant and writes that he finds the roving patrols to fit in the doctrine.

Also like in Camara, this use of roving patrols is not to enforce the criminal law, but is administrative in nature—to apprehend and remove individuals present without authorization.

These considerations direct his finding that under limited circumstances, there could be a constitutionally adequate equivalent of probable cause to permit roving patrol searches in border areas.

Because the exceptions do not apply, Justice Powell notes that Border Patrol officers needed consent or a warrant to search Almeida-Sanchez's vehicle as they did.

[23] Justice Powell concludes his opinion by proposing relevant factors to consider in evaluating whether there is probable cause (or a functional equivalent) for a roving patrol.