What constitutes a search or seizure for Fourth Amendment purposes?

2 We also note that simply turning away a vehicle when no legitimate reason for entry is given may not constitute a search or a seizure for Fourth Amendment purposes. In order for there to have been a "search," "the police must have physically intruded into 'a constitutionally protected area.' " See 1 LaFave, Search & Seizure 2.1(a), at 302-03 (2d ed. 1987). Refusing entrance does not intrude into any such area. Similarly, a "seizure" requires that an officer restrict the liberty of an individual such that a reasonable person would not believe that he was free to leave. Id. (citing United States v. Mendenhall, 446 U.S. 544, 100 S.Ct. 1870, 64 L.Ed.2d 497 (1980)). In Sheppard v. Beerman, 18 F.3d 147 (2d Cir.), cert. denied, 513 U.S. 816, 115 S.Ct. 73, 130 L.Ed.2d 28 (1994), we held that no Fourth Amendment "seizure" took place when a fired court employee was escorted from the courthouse. We reasoned that because the plaintiff was free to go anywhere in the world, except the courthouse, he had not been "seized." Id. at 153. Here, the plan was that motorists who were denied entry for lack of any legitimate reason to go into the area were free to go anywhere else.