I ask that question in all seriousness. Are we a nation of laws, or are we a Banana Republic where the government can do whatever it wants?
In a Banana Republic, if El Presidente doesn't like you, he makes up a law like "Felonious Mopery on the High Seas", makes the penalty death upon conviction, then has you arrested and charged with said crime. You are tried the next morning, found guilty before lunch and executed that afternoon.
In a nation of laws, the police have to wait for a complaint. This means Joe Blow goes down to the local precinct and makes an official statement on the order of Paul Somesuch stole my car (or whatever)." The police would then look up the laws for Tennessee and find that § 39-14-103 defines theft of property. § 39-14-105 breaks out what class of crime it is. Considering Paul stole Joe's $30,000 Lexus, Paul will likely be getting charged with a Class C Felony upon his capture. The police can also witness a crime, or find evidence of a crime (e.g., a human body).
In these cases, the police start with the indication that a crime has been committed. During the investigation the confirm what crime has been committed, then locate the person who their evidence convinces them committed the crime. An arrest is made and the perpetrator and the evidence are turned over to the District Attorneys who then evaluate if they can convict the accused, and on and on. Just watch Law and Order for the whole process.
What we have whenever there is a Special Investigator appointed to look into a high profile, politically charged situation, we start out with investigating a person to see what crimes they have committed, then charging them with those crimes. I didn't like the Starr investigations into the Whitewater case in the 90's and I don't like Mueller's investigation into the "Trump-Russia collusion" today. Both of these were legal hunting licenses. "Get these people and anyone near them for anything and everything you can."
This past Monday, George Papadopoulos, Paul Manafort and Rick Gates were charged by Mueller. Let's look at these.
George Papadopoulos pleaded guilty to "lying to investigators." His lie? At one point in time he was trying to set up a meeting with an overseas professor who "had substantial connections with Russian officials." He stated that he tried doing this before becoming a part of the Trump Campaign. He stated later that he tried to set this meeting up AFTER he became a part of the Trump Campaign.
You can be caught for "making false statements" just by rewording an answer to a question asked multiple times. Because when you reword an answer, you 99% of the time leave out a small tidbit of information, or add said small tidbit that you didn't include before. You could also change an answer because you remembered something you didn't before, you are nervous or a dozen more reasons. That change in an answer, not matter how small is all they need to get you.
Manafort and Gates were charged with conspiracy against the United States, conspiracy to launder money, failing to register as a foreign agent, making false statements, and multiple counts of failing to file reports for foreign bank accounts. From all accounts, these offenses predate their involvement in the Trump Campaign by months or years.
I'm not a lawyer and I didn't stay at a Holiday Inn Express last night. I cannot speak on the viability of these charges against Manafort and Gates. I will say something on their first charge. Conspiracy against the United States (Title 18, Chapter 19, Section 371 of the US Code) is like Section 134 of the Uniform Code of Military Justice. It is a "We can't find another law to convict you with, so we'll get you with this one." It can be used against a group who "commit any offense against the United States, or to defraud the United States, or any agency thereof in any manner or for any purpose". If the government feels at any time that two (or more) people worked together do deprive the US government of money or property it deems to be theirs, they can get you on this charge. It is so broad you could drive a fleet or tractor-trailers through it.
Again, are we a nation of laws where you investigate a crime and find the person who committed it, or are we a Banana Republic where we investigate the person until we find a crime they committed?