边境巡逻警察常规搜车不需要 warrant。根据 Nolo, 在边境, one has diminished right, The government has a unique interest in policing its borders, and people have a lower reasonable expectation of privacy where borders are involved. In general, officials have more search-and-seizure leeway at and around the border.

跟过机场体育场这些地方的安检，随身包过传送带，还可以被打开快快翻一下类似，工作人员不需要你的同意就可以搜。这是1973年以来的操作, 以前不这样

On November 10, 1972, a trio of hijackers threatened to fly Southern Airways Flight 49 into a nuclear reactor at Oak Ridge National Laboratory. As a direct response to this incident, the Federal Aviation Administration required all airlines to begin screening passengers and their carry-on baggage by January 5, 1973.

What Is Classified as Probable Cause?

In most situations, police need a vehicle warrant to search your car.

However, if an officer can state a probable cause for his belief that there is an illegal item or contraband in your car or evidence of a crime in your car, he is authorized for a search without a warrant

警察有搜车的权力。你有不同意他搜车的权力。如果你不同意，警察还是搜了你的车。你在后面的司法过程有优势，或者可以说你的律师可以在这个上面做文章。

有probably cause就可以搜车。你可以拒绝，通常结果是警察会当场逮捕你，然后就可以随便搜了。

没有搜查令，警察不能搜你任何的私人物品。

但他们一般会诱导下问， 比如为了我们彼此的和谐，为了让你早点走等等，我可以搜你的车吗？

你同意后，他们就免责了。

但你坚持不让他们搜， 他们就不能搜。网上无数教学视频，但要小心被警察搞，说你意图袭警等等。

如果你不同意搜，他会把你带回警局，同时申请搜查令再搜吧。

这个案例中警犬的作用就是制造probable cause. 实际上警犬受handler训练，可以在verbal or non-verbal cue下作出可以解释为“这里有毒品”的动作或姿势。作为被搜的人，只要一口咬定”I do not consent to the search”, 你将来庭审就有可能exclude the evidence found in the search (that later was deemed by the court as without a probable cause). 但是一同意搜查就没戏了。

不明白，为什么“警员笑疯”？