President Trump accused Barack Obama of wiretapping Trump Tower before the election.

The Washington Post dismissed the charge:

Trump offered no citations nor did he point to any credible news report to back up his accusation, but he may have been referring to commentary on Breitbart and conservative talk radio suggesting that Obama and his administration used "police state" tactics last fall to monitor the Trump team.

The Washington Post, a member of the Opposition Party, does not believe that Breitbart is credible.  Breitbart reported that the Obama administration sought a FISA warrant in June 2016, which was denied, but did obtain a FISA warrant in October 2016.

Assuming that a warrant was obtained in October to tap Trump Tower, had such surveillance produced anything of value, you can bet that Obama would have disclosed the results of the investigation.  The fact that Obama did not release any such information is further evidence that the "Russian interference" claim by the Opposition Party is pure nonsense designed to weaken the Trump presidency.

The standard for obtaining a warrant is to present to a judge facts from a reliable source that a crime is being committed or was committed, and that the place to be searched contains relevant information.  Only the prosecutors present the warrant application to the judge.  The person to be searched is not present to rebut the charges.  But the standards under FISA are more lenient:

Under the Fourth Amendment, a search warrant must be based on probable cause to believe that a crime has been or is being committed. This is not the general rule under FISA: surveillance under FISA is permitted based on a finding of probable cause that the surveillance target is a foreign power or an agent of a foreign power, irrespective of whether the target is suspected of engaging in criminal activity. However, if the target is a "U.S. person," there must be probable cause to believe that the U.S. person's activities may involve espionage or other similar conduct in violation of the criminal statutes of the United States. Nor may a U.S. person be determined to be an agent of a foreign power "solely upon the basis of activities protected by the first amendment to the Constitution of the United States.

We do not know who were the targets of the warrant.  The warrant application must be approved by the attorney general, which means that Loretta Lynch had to approve it.  FISA warrants are usually granted.

The application for a FISA warrant must follow the following procedure:

Under FISA, the Justice Department reviews applications for counterintelligence warrants by agencies before submitting them to the FISC. The Attorney General must personally approve each final FISA application.

The application must contain, among other things:

• a statement of reasons to believe that the target of the surveillance is a foreign power or agent of a foreign power, (subject to the relevant amendments made by the USA-PATRIOT Act, discussed below)
• a certification from a high-ranking executive branch official stating that the information sought is deemed to be foreign intelligence information, and that the information sought cannot reasonably be obtained by normal investigative techniques;
• statements regarding all previous applications involving the target;
• detailed description of the nature of the information sought and of the type of communication or activities to be subject to the surveillance;
• the length of time surveillance is required;
• whether physical entry into a premises is necessary, and
• proposed procedures to minimize the acquisition, use, and retention of information concerning nonconsenting U.S. persons.

For U.S. persons, the FISC judge must find probable cause that one of four conditions has been met:

(1) the target knowingly engages in clandestine intelligence activities on behalf of a foreign power which "may involve" a criminal law violation;

(2) the target knowingly engages in other secret intelligence activities on behalf of a foreign power under the direction of an intelligence network and his activities involve or are about to involve criminal violations;

(3) the target knowingly engages in sabotage or international terrorism or is preparing for such activities; or

(4) the target knowingly aids or abets another who acts in one of the above ways

It appears that the Obama administration used the FISA court to obtain a warrant to spy on Trump, using the "Russian interference" as a reason and hoping to find something to use against him.

We had a Watergate Committee to investigate the break-in of the headquarters of the DNC, supposedly to obtain information on the Democrat candidates.  The question was what Nixon knew and when he knew it.  Now we have the use of the FISA warrant to obtain information about Trump.

We need an investigation to determine the basis of the warrant.  What facts were alleged?  Who authorized seeking the warrant?  Why was it the warrant sought?  Who was the target of the warrant?

It is difficult to believe that Attorney General Lynch would have approved wiretapping Donald Trump, Trump Tower, or members of his campaign team without the knowledge and approval of Obama.

Did Obama know the warrant was sought?  When did he know?  Did he authorize it, even if he did not order it?  Why would he authorize it?

As the Democrats repeatedly say, such serious charges demand a full investigation and a special prosecutor.