Summary:

Islamic scholars of today are claiming that Ta'zir punishment for adultery/rape will still be given even if there are fewer than 4 male eyewitnesses present.
But this is a BID'AH (i.e. Evil Innovations) as it changes the original RULING which is based upon alleged Divine Wisdom.
This new law proves only one thing, i.e. Muslims consider themselves wiser than Divine Allah and they can make better laws than Allah.
But Muslims are forced to commit this Bid'ah while the original Sharia Ruling is extremely illogical.
And it becomes even more illogical that witnesses will be lashed 80 times if their number is less than 4, even if the remaining 3 are telling the Truth.

And here is proof that these Islamic scholars are committing a Bid'ah today by changing the Sharia.

Mughirah (a prominent companion) during the era of the caliphate of 'Umar Ibn Khattab. He was a friend of 'Umar, and he wanted to save him.

Saudi Scholar Sheikh Albani recorded the following tradition (link):

حدثنا أبو بكر قال حدثنا ابن علية عن التيمي عن أبي عثمان قال: لما قدم أبو بكرة وصاحباه على المغيرة جاء زياد فقال له عمر: رجل لن يشهد إن شاء الله إلا بحق، قال: رأيت انبهارا ومجلسا سيئا فقال عمر: هل رأيت المرود دخل المكحلة، قال: لا، قال: فأمر بهم فجلدوا.

After Abu Bakrah and his two companions (i.e. all together 3 people) had testified against al-Mughirah (that he committed adultery). Ziyad (the 4th witness) came. So, ‘Umar said, “He is a man who will never testify, Allah willing, except with the truth.” He (Ziyad) said, “I saw a spectacle and an evil assembly”. So, ‘Umar said, “Did you see the kohl stick (i.e. the male private organ of al-Mughirah) enter the kohl container (i.e. the female private organ of the woman)?” He (Ziyad) replied, “No.” Therefore, he (‘Umar) ordered that they (Abu Bakrah and his two companions) be whipped.

Sheikh al-Albani said about this tradition:

قلت: وهذا إسناد صحيح على شرط الشيخين.

I say: This chain is sahih upon the standard of the two Shaykhs (i.e. Sahih Bukhari and Sahih Muslim).

This same tradition has also been recorded through multiple ways, which have Sahih (authentic) chains (link).

Similarly, this tradition also proves that there is no lesser Ta'zir punishment if 4 witnesses are not present:

Sunan Abi Dawud, 2253:

‘Abd Allah (bin Mas’ud) said “We were in the mosque on the night of a Friday, suddenly a man from the Ansar entered the mosque”. And said “If a man finds a man along with wife and declares (about her adultery) you will flog him. Or if he kills you, you will kill him or if keeps silence he will keep silence in anger. I swear by Allaah, I shall ask the Apostle of Allaah(ﷺ) about it”. On the next day he came to the Apostle of Allaah(ﷺ) and said “If a man finds a man along with wife and declares (about her adultery) you will flog him. Or if he kills you, you will kill him or if keeps silence he will keep silence in anger.” He said “O Allaah, disclose”. He kept on praying until the verses regarding invoking curses (li’an) came down “As for those who accuse their wives but have no witnesses except themselves.” So, the man was first involved in this trial among the people. He and his wife came to the Apostle of Allaah(ﷺ). They invoked curses on each other. The man bore witness before Allaah four times that the thing he said was indeed true. He then invoked curse of Allaah on him for the fifth time if he was a liar. She then wanted to invoke curses of Allaah on him. The Prophet (ﷺ) said “Do not do that. Bust she refused and did so (i.e., invoked curses). When they returned he said “Perhaps she will give birth to a black child with curly hair.

The Journey of 4 Male Eyewitnesses:

The journey of 4 male eyewitnesses in the case of adultery started with the incident of IFK, where 'Aisha was charged with adultery. There were 3 companions, who testified against 'Aisha. Upon that, Muhammad claimed the revelation of a new verse, which put the minimum limits of eyewitnesses to 4.
Muhammad was angry with those 3 companions who witnessed against 'Aisha. By doing so, they also put a question on the prophethood of Muhammad.
Thus, Muhammad also claimed in that new revelation if the number of witnesses is less than 4, then the remaining witnesses will be lashed 80 times in the name of Qadhaf (i.e. false testimony). Thus, those 2 or 3 witnesses will be lashed, even if they are telling the truth.
And then Muhammad claimed the revelation of a new verse: "Pure men get only pure women (Quran 24:26)" i.e. 'Aisha is pure while she got a pure husband like Muhammad.

You can read all the details here: IFK incident: A Revelation, which itself turned against Muhammad + Pure men have only pure wives + 4 witnesses in case of fornication

The IFK incident was the start of this journey.

The consequence of this Sharia Rule of 4 eyewitnesses:

Although Muhammad saved 'Aisha through this ruling, and 'Umar successfully saved Mughira too, nevertheless, this became a major problem for the rest of Muslim society.

Muslim men were indulging mostly in adultery with slave women of other people.
Since it was impossible to bring such 4 male eyewitnesses, thus it became impossible to punish them (i.e. men and slave women).
There were red-light areas where prostitution was done (mostly through slave women). Still, no punishment could be given to them due to this ridiculous Sharia law of 4 eyewitnesses.
Even free wives inside the house indulged in adultery with relatives of their husbands or with male slaves. (Remember, Islam has another ridiculous law that an adult male slave becomes Mahram to the wives and daughters of the owner as soon as he is bought from the market. He can enter the house and stay alone under one roof with the wives and daughters of the owner. Please read the details here.
Another huge problem occurred in the cases of RAPE. Muslim men raped slave women and also free women, and it was impossible to bring 4 male eyewitnesses to punish them.

During the whole 1400 years of the history of Islam, there is hardly any recorded case where 4 male witnesses were present on the spot, who saw kohl stick going into the container.

Why did Allah fail to reveal a single clear verse about rape in the Quran?

Even if we consider the arguments of present-day Islamic apologists, who claim that 4 male eyewitnesses are not needed in the case of rape, the questions still remain:

If Allah truly exists and possesses knowledge of the unseen future, and He knew that the entire Ummah would misunderstand this issue for 14 centuries,
and if Allah also foresaw that millions of vulnerable women, including slave women, would suffer due to this mistake (as they would be denied justice without the testimony of 4 male eyewitnesses),
Why did He not reveal a single clear verse in the Quran to clarify the number of witnesses required in rape cases, and if the testimony of women would be accepted or not?

The Quran is a big fat book, yet Allah filled it ONLY with boasting about his powers and some old stories. Why was he unable to send Sharia orders wisely?

We come only to the conclusion that there exists no all-Knowing and all-Wise and 100% perfect flawless Allah in the heavens, but it was Muhammad who was making the revelation on his own. Since Muhammad was only a human, thus we see human mistakes and non-perfection in Sharia too.

Bid'ah in 4 eyewitnesses ruling by Pakistani Muslims:

The radical Islamization of Pakistan started under the rule of General Zia-ul-Haq, and for the first time the "The Offence of Zina Ordinance, 1979" was introduced. It had the original Sharia rulings, i.e.:

Four eyewitnesses are required for adultery and rape.
The testimony of a woman is not accepted, even if she is the rape victim herself.
All these 4 males should also be Muslims (i.e. testimony of non-Muslims is not accepted against any Muslim. This means, if a Muslim male raped a non-Muslim woman, then the testimony of neither the victim nor her non-Muslim husband will be accepted).
All 4 Muslim males should also be truthful people and abstain from major sins.
And they saw it so clearly as a kohl stick going into the container.
And if the number of witnesses is not 4, then the rest of the witnesses will be lashed 80 times for Qadhaf (i.e. false testimony, even if they are telling the truth).

This actual Sharia ruling and Pakistani law were extremely ridiculous:

There were red light areas in all cities of Pakistan, and it was impossible to punish people for adultery in the presence of these actual Sharia laws.
Moreover, all those women, who were rape victims, then went to the police to register the case, they were themselves imprisoned, while all of them failed to bring 4 eyewitnesses. And they were themselves punished with 80 lashes for committing the crime of Qadhaf.

Thus, Pakistani Muslims were compelled to make changes to the original Sharia law, and in 2006, they introduced the following Bid'ahs (link):

Punishment will still be awarded if the number of witnesses will be less than 4.
But this punishment will be lesser than the original punishment of stoning/100 lashes of the original Sharia Ruling. They gave it the name of Tazir punishment.
And if there are not 4 witnesses, still the 2 or 3 witnesses will not be punished for Qadhaf (i.e. the false testimony).
Similarly, the rape victims (i.e. the women) will also not be punished for Qadhaf if they fail to provide 4 witnesses.

Nevertheless, these new laws are Bid'ahs while:

Muhammad indeed punished 3 companions with Qadhaf, while the 4th witness was not present.
Neither Muhammad nor 'Umar went for any lesser Ta'zir punishment. But they gave absolutely no punishment to the accused ones.

Bid'ah by Indonesian Muslims in the ruling of 4 eyewitnesses

Unfortunately, Indonesian Muslims have also been radicalized lately.

They also tried to introduce Sharai Hudood laws, but despite being radical Muslims, they failed miserably.

Instead of Sharia Hudood laws, they had to introduce a lot of Bid'ahs, in order to stop premarital sex or adultery. These newly innovated laws are as under:

No 4 eyewitnesses are needed, who are Males, who are Muslims, who are honest, and who don't indulge in major sins.
It is not needed that they saw the action like a kohl stick going into the container.
But even if the spouse, parents, or children report it, then it is enough to award people with punishments.

What if a girl gets pregnant without marriage in an Islamic state?

What did Imam Malik say about rape?

Malik said, "The position with us about a woman who is found to be pregnant and has no husband and she says, 'I was forced,' or she says, 'I was married,' is that it is not accepted from her and the hadd is inflicted on her unless she has a clear proof of what she claims about the marriage or that she was forced or she comes bleeding if she was a virgin or she calls out for help so that someone comes to her and she is in that state or what resembles it of the situation in which the violation occurred." He said, "If she does not produce any of those, the hadd is inflicted on her and what she claims of that is not accepted from her."
Muwatta Malik Book 41, Hadith 15

How is this relevant to Muslims today?

Here are some examples below:

Bariya Ibrahim Magazu is a Nigerian teenager who was lashed 100 times after she became pregnant before marriage. She claimed she had been raped by several men who had loaned money to her father. However, the state she lived in, Zamfara, had transitioned to Sharia law, and the male judges presiding over her case acquitted the accused men but upheld her hadd sentence.
Safiya Hussaini is another Nigerian woman who was sentenced to stoning after becoming pregnant following her divorce. Her state, Sokoto, had also recently transitioned to Sharia law. She claimed that she had been raped repeatedly by her neighbour, but the court acquitted her neighbour while sentencing her to death. Fortunately, she was acquitted by a higher court, because her alleged adultery must have happened before Sharia was actually implemented in Sokoto.